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# QuestionHelpful RatingTags
285 Awaiting user Action...no answer posted yet A company is filling bags of rock salt to a level of 50 pounds. It believes that all bags are filled correctly, but would like to use a hypothesis test with an alpha of 0.05 to check this belief. The company will be using samples of 100 bags from each run to do the test. State the null and alternative hypotheses:
283 Awaiting user Action...no answer posted yet The lengths of pregnancies are normally distributed with a mean of 264 days and a standard deviation of 25 days. If 100 women are randomly selected, find the probability that they have a mean pregnancy between 264 days and 266 days.Z-Score, Area between
282 There is an answer for this Question In normal distribution with mean 55 and atandard deviation 10,the area to the right of 55 is a) 0.6 b) 0.8 c) 0.9 d) 0.7537.14
281 Awaiting user Action...no answer posted yet in a normal distribution curve with mean as 55 and standard deviation as 10 what will be the area on the right side of the curve and how?
280 Awaiting user Action...no answer posted yet what will be the area covered by a curve on the right side if the sd =10 and mean 55
279   what are the advantages of a using a power equation
278 Awaiting user Action...no answer posted yet out of a random sample 167 students pass an exam out of the 300. how do you calculate an exact 99% confidence interval for the proportion of sudents who passed the exam?exact interval, Confidence Intervals
277 Awaiting user Action...no answer posted yet If an A is given to a student who scores 90% or above, what would the minimum z-score be for a 300 multiple choice question test with a mean of 195 and a standard deviation of 30Z-Score
276 Awaiting user Action...no answer posted yet Why is population shape of concern when estimating a mean? What does sample size have to do with it?
275 Awaiting user Action...no answer posted yet The lowest 25% of the normal distribution falls below what z-score and t-scoreT score, Z-Score
274 Awaiting user Action...no answer posted yet The Web-based company Oh Baby! Gifts has a goal of processing 95 percent of its orders on the same day they are received. If 485 out of the next 500 orders are processed on the same day, would this prove that they are exceeding their goal, using á = .025? (See story.news.yahoo.com accessed June 25, 2004.)Confidence Intervals
273   Discuss the characteristics of probability within the context of rolling a die.
272 Awaiting user Action...no answer posted yet What is z-score? what information is provided by a z-score?
271 Awaiting user Action...no answer posted yet which type of data set can the mean not be calculated?skew, mean, Geometric Mean, Median
269 Awaiting user Action...no answer posted yet A classical experiment in extrasensory perception (ESP) consists of asking a subject to tell, without looking, the suit of each card in a deck of Zener cards. There are five suits in the deck so the probability of a chance match between the guess and the card is 1/5 or .20. If only chance is operating, you would expect a subject to get 20 matches in 100 guesses (.20 X 100 =20). The standard deviation for this mean of 20 is 4. What is the probability of a subject making 23 or more matches in 100 guesses? What is the probability of 27 or more matches in 100 guesses? Suppose a friend of a friend claimed to have ESP and agreed to sit just on time and guess at 100 cards. Suppose she made 36 matches. Calculate the probability of this many, or more, matches if only chance is at work, and carefully write a conclusion.Z-Score, Binomial Probability, Normal Approximation, binomial
268   How would you demonstrate the Central Limit Theorem to classmates
267   how can i compute for the standard scores when i don't know what the SD is?
266 Awaiting user Action...no answer posted yet what is the difference between percentage and percentile?specially in cat like exams.Percentile
265   An auditor reviewed 25 oral surgery insurance claims from a particular surgical office, determining that the mean out-of-pocket patient billing above the reimbursed amount was $275.66 with a standard deviation of $78.11. (a) At the 5 percent level of significance, does this sample prove a violation of the guideline that the average patient should pay no more than $250 out-of-pocket? State your hypotheses and decision rule. (b) Is this a close decision? Write the Null & Alternative Hypotheses Set the Alpha Level Find the Critical Value(s) & Set the Decision Rule Calculate the Test Statistic Compare your Test Statistic with the Critical Statistic Make the Decision Write a brief paragraph discussing your findings. Find the P-Value for your Test. Explain how your P-Value could have been used to make the decision.
264   9.62 The Web-based company Oh Baby! Gifts has a goal of processing 95 percent of its orders on the same day they are received. If 485 out of the next 500 orders are processed on the same day, would this prove that they are exceeding their goal, using á = .025? (See story.news.yahoo.com accessed June 25, 2004.) Write the Null & Alternative Hypotheses Set the Alpha Level Find the Critical Value(s) & Set the Decision Rule Calculate the Test Statistic Compare your Test Statistic with the Critical Statistic Make the Decision Write a brief paragraph discussing your findings. Find the P-Value for your Test. Explain how your P-Value could have been used to make the decision.
263 Awaiting user Action...no answer posted yet Determine the critical value Za/2 that corresponds to 94% level of confidence Compute the 90% confidence interval about m if the sample size, n, is 55. How does does increasing the sample size affect the margin of error, E?Critical Value, Confidence Intervals, Margin of Error
262 Awaiting user Action...no answer posted yet with a mean of 150 and a standard deviation of 15 what is the probability of a student having a weight of less than 178 lbs.Z-Score
261 Awaiting user Action...no answer posted yet If your hypothesis is not correct, can the data collected still be used within a subsequent analysis.Hypothesis Test, p-value
260 Awaiting user Action...no answer posted yet Suppose that the scores of architects on a particular creativity test are normally distributed. What percentage of architects have Z scores (a) above .10, (b) below 10, (c) above .20, (d) below .20, (e) above 1.10, (f) below 1.10, (g) above -.10, (h) below -.10?
259 There is an answer for this Question What is the formula used to get percentile from z-score? I have z-scores but am using excel and want to be able to type in a formula to figure percent instead of coming here and continuing to figure it out.50NORMSDIST
258   there is a -1.64 because this is a one-tailed directional test at the .05 level of significance. Why?
257 Awaiting user Action...no answer posted yet A company is filling bags of rock salt to a level of 50 pounds. It believes that all bags are filled correctly, but would like to use a hypothesis test with an alpha of 0.05 to check this belief. The company will be using samples of 100 bags from each run to do the test. State the null and alternative hypotheses:Null Hypothesis , Alternative Hypothesis
256   19. A doctor reports that he/she has been experiencing a 15% rate of no-shows on appointments. Among 150 appointments, find the probability that there will be fewer than 20 no-shows. Use the normal distribution to approximate the binomial distribution. _________ Convert the binomial probability to a normal distribution by using the correction for continuity _______________ n = _______ p = _______ q = _______ µ = _______ ó = _______
255   A coin was flipped 60 times and came up heads 38 times. (a) At the .10 level of significance, is the coin biased toward heads? Show your decision rule and calculations. (b) Calculate a p-value and interpret it
254   Body Temparatures. Human body Temp have a mean of 98.20F and standard deviation of 0.62F. Convert the given temparatures to z scores. A. 97.5F B. 98.60F C. 98.20F Lenght Of Pregnancy. A woman wrote to Dear Abby and claimed that she gave birth 309 days after a visit from her hushand , who was in the Navy. Lengths of pegnancies have a mean of 268 days and a standard deviation of 15 days. Find the z score for 308 days. Is such a length unusual? What do you conclude? Ages of best Actresses. Use the 76 sorted ages of best actresses listed in 3-4 a. find the interquartile range b. find the midquartile. c. find the 10-90 percentile range. d. does p50 = q2? if does p50 always equal q2 e. does q2 =, (q1 + q3)/2? if so,does q2 always equal (q1 + q3)/2 15. 25 17. 40 19. p10 23. p33 24. p66
253 Awaiting user Action...no answer posted yet What are the 2 advantages of using Z power? If the z score is less than 0, what can be said of the corresponding raw score? If the z score is greater than 0, what can be said of the raw score? If the z score is equal to 0, what can be said of the raw score?Z-Score
252   Examine the data below showing the weights (in pounds) of randomly selected checked bags for an airline's flights on the same day. (a) At α = .05, is the mean weight of an (a) At α = .05, is the mean weight of an international bag greater? Show the hypotheses, decision rule, and test statistic. (b) At α = .05, is the variance greater for bags on an international flight? Show the hypotheses, decision rule, and test statistic.
251   How can I calculate the z-score for 2 test data that come from 2 tester, eg: 378 and 362?
250   1)For n = 49, find the 90% confidence interval for x bar = 85 and ó = 2. Do not round! 2)A purchasing agent for a national chain of seafood restaurants wants to estimate the mean weight of shrimp in a large catch. How many shrimp should be sampled from the catch to be 95% confident that the sample mean will be off from the actual mean weight by no more than 1.4 grams. Assume that ó = 4 grams. 3)Find the 99% confidence interval for a sample size of 25, x bar = 150, and s = 3. Round your final answer to two decimal places.
249 Awaiting user Action...no answer posted yet A nationally standardized test is scaled so that the normally distributed scores have a mean of 80 and a standard deviation of 10 in the population. If we have a group of 25 scores from this test, and compute the mean, what is the probability that this mean will be: a. Below 82? b. Below 76? c. Above 80?Z-Score
248   the class ends the year with a mean of 68 and a stadard deviation of 9, the prof decides to bell curve the marks so that the top 10% gets an A (80%). What z score must a student achieve to recieve an A? What raw grade does this correspond to?
247 Awaiting user Action...no answer posted yet Jeff: Can you possibly share the actual formula you are using in this application to produce the Adjusted Wald calculations? ThanksAdjusted Wald, Z-Score, Confidence Intervals
245   Use the traditional method to test the given hypothesis. Assume that the samples are independent and that they have been randomly selected A researcher finds that of 1,000 people who said that they attend a religious service at least once a week, 31 stopped to help a person with car trouble. Of 1,200 people interviewed who had not attended a religious service at least once a month, 22 stopped to help a person with car trouble. At the 0.05 significance level, test the claim that the two proportions are equal.
244   Mean output of solar cells of three types are measured six times under random light intensity over a period of 5 minutes, yielding the results shown. Research question: Is the mean solar cell output the same for all cell types? SolarWatts Solar Cell Output (watts) Cell Type Output (watts) A 123 121 123 124 125 127 B 125 122 122 121 122 126 C 126 128 125 129 131 128
243   Examine the data below showing the weights (in pounds) of randomly selected checked bags for an airline's flights on the same day. (a) At α = .05, is the mean weight of an (a) At α = .05, is the mean weight of an international bag greater? Show the hypotheses, decision rule, and test statistic. (b) At α = .05, is the variance greater for bags on an international flight? Show the hypotheses, decision rule, and test statistic. Luggage International (10 bags) Domestic (15 bags) 39 47 29 37 43 54 48 36 33 42 46 28 33 29 32 39 54 34 43 35 69 62 38 39 39
242   When would you use regression correlation at your place of employment, in your education, or in politics
241   a university's administrator proposes to do an analysis of the proportion of graduates who have not fuond employment in their major field one year after graduation. In previous years, it was 12%. He wants hte margin of error to be withing .04 at a 99% confidence interval. Find the minumum sample size.
240   Estimate probability P(6) for a binomial experiment within = 18, p = 0.30 by using the normal distribution
239 There is an answer for this Question I have a data set where n=20. My problem is to find the score at exactly the 75th percentile assuming normality. I know the formula for z-score, the mean, and the standard deviation. How do I do this problem?81.43Z-Score
238   A random sample of rivets from 2 suppliers were compared to see what the mean diameter was from each and a test to determine whether the population means were the same for the 2 suppliers. Now a comparison of the variation in diameter is needed. Company A has a mean of 0.375 and a standard deviation of 0.00082. Company B has a mean of 0.375 and a standard deviation of 0.03808. What is the appropriate hypothesis test to determine if the 2 suppliers have equal standard deviations (using a significance level equal to 0.05)?
237   A sample of 100 one-dollar bills from the Subway cash register revealed that 16 had something written on them besides the normal printing (e.g., “Bob ﾀ Mary”). (a) At α = .05, is this sample evidence consistent with the hypothesis that 10 percent or fewer of all dollar bills have anything written on them besides the normal printing? Include a sketch of your decision rule and show all calculations. (b) Is your decision sensitive to the choice of α? (c) Find the p-value.
234 There is an answer for this Question The third quartile of the age at marriage for females in US last year was 29.5 years. What percentage of women who married in the US last year were older than 29.5 years?Quartile
233 There is an answer for this Question Between what two values of Z will 88% of the middle data values fall between?Z-Score
232 There is an answer for this Question If a distribution of test scores is normal with a mean of 78 and a standard deviation of 11, what percent of the area lies below 60Z-Score
231 There is an answer for this Question A person gets 14/20 on a test in which each question has 5 answer choices. What is his 95% CI for his score?
230 There is an answer for this Question a score that is 8 points above the mean corresponds to a z-score=0.05 What is the population standard deviation?Standard Deviation, Z-Score
229 There is an answer for this Question Hi, what is the formula for converting z-scores to percentiles? I want to build a tool in Excel so i can get percentiles from test scores on normally distributed psychometric tests. Thanks, Stephen100NORMSDIST
227   how actually p value represents a distribution pattern whether it is normal or not? u explain the anderson-darling test regarding the normal graph
226   thank u for the information. but actually i need the two tailed z-score graph with the outliers if it has. if u need the values of arsenic concentration of different locations i can give u? please give me the answer. thanks
225   How do we calculate the upper and lower limits of one sided and two sided 95% confidence level of difference in proportion when comparing two groups in clinical research.Could You kindly help with some formula for calculating these.
224 There is an answer for this Question I have some datas of arsenic concentration blockwise. can it be possible to compare the datas graphically, for blockwise distribution of the arsenic in groundwater samples?Interaction Plot
222 There is an answer for this Question Fitness club surveys randomly selected members and found that the average weight of those questioned is 157 lb. Is this a parameter or a statistic?Parameter, statistic
219 There is an answer for this Question A z score of 1.04 shows a percentage value of?75Z-Score
218 There is an answer for this Question what are the key terms in a verbal hypothesis that signify whether you are conducting a one-tailed or two-test? Give an example and explain your answer.100Hypothesis Test, One-Tailed Area
217   Volunteers at a teenage distress center have been assigned based on their skills and expertise. It's assumed that 40% are drug related, 25% sex related, 25% stress, and 10% education. For the study sample of 120 calls per month were categoruzed as follows Observed frequencies: Drug (52) Sex (38) Stress (21) Education (9) Total 120. Apply chi-squared goodness of fit to test the hypothesis of assumed distribution of calls. Interpet results for the purposes of staff allocation at the distress center.
215 There is an answer for this Question Annual starting salaries for college graduates with degrees in business administration are generally expected to be between $30,000 and $45,000. Assume that a 95% confidence interval estimate of the population mean annual starting salary is desired. What is the planning value for the population standard deviation (0 decimals)?Standard Normal Curve, Confidence Intervals, Standard Deviation, Normally Distributed
214 There is an answer for this Question I am charged with sampling expense report submissions for accuracy. We get 8000 T&E claims, and want to sample a subset making inferences about the population. I can probably get a good estimate of the populations' SD, how would i calculate required sample size? I think i would be measuring the delta between actual and claimed - the majority be 0. Is this a one sided issue? Thanks in advance - FT Also, would i need the acceptable level first? ie. we would accept an average difference of $5? How can i work backwards if the first sample size yields an average of $1? (if that made sense)1-sample t-test, Confidence Intervals, Sample Size
213   Let X be a random variable with the following probability distribution. Find the expectation and variance E(X) Var (X)of X. Value x of X P(X=x) 10 0.10 20 0.30 30 0.05 40 0.10 50 0.05 60 0.40 What formula would I use? Can you break it down into baby steps so I can understand how you got the answer? Thanks
212 There is an answer for this Question How would I figure out a 90% and 95% confidence interval for the below informaion? What would be the formula? Can I figure this out in Excel or Megastat? How would I do that? Men Female count 53 47 mean 36,492.92 24,451.51 sample variance 340,313,003.72 154,893,232.30 sample standard deviation 18,447.57 12,445.61 standard error of the mean 2,533.97 1,815.38t-distribution, Confidence Intervals, TINV, Margin of Error
211 There is an answer for this Question State the main points of the Central Limit Theorem for a mean. B. Why is population shape of concern when estimating a mean? What does sample size have to do with it?Central Limit Theorem, Sample Size
210 There is an answer for this Question My local coffee house sells Colombian coffee beans to supermarkets in bags labelled 100g each. The tolerance of the automatic filling machine, leads to weights of bags being approximately Normally distributed with standard deviation 5g. The target mean weight is set at 106g (i.e. the filling machine is set at 6% overfill). Find the percentage of bags which are below the labelled weight. Show the z-score. How do i work this out?87.14Z-Score
209 There is an answer for this Question In 1992, the FAA conducted 86,991 pre-employment drug tests on job applicants who were to be engaged in safety and security relatd jobs and found that 1,143 were positive a. construct a 95% confidence interval for the population proportion of positive drug test. b. why is the normality assumption not a problem, despite the very small value?Central Limit Theorem, binomial, Normal Approximation, Confidence Intervals
208 There is an answer for this Question I am comparing 2 proportions of patients (before and after the introduction of a new quality-of-care project). The project is expected to reduce the proportion of patients with a particular disease. Is a one-sided test of significance enough to prove that?1001-Sided Test, Hypothesis Test
207 There is an answer for this Question Suppose that the scores of architects on a particular creativity test are normally distributed.What percentage of architects have Z scores. (a) above .10, (b) below .10, (c) above .20, (d) below .20, (e) above 1.10, (f) below 1.10, (g) above -.10, (h) below -.10?75.71Z-Score
206 There is an answer for this Question The variable Z has a standard Normal distribution. a) Find the number z that has cumulative proportion 0.85. b) Find the number z such that the event ZZ-Score
205 There is an answer for this Question Find the number z that has cumulative proportion 0.8Z-Score
204 There is an answer for this Question What does a z value mean?75Z-Score, Z-value, Standard Score
203 There is an answer for this Question How to determine the sample size for comparing mulltiple parameters like Height , weight, Blood pressure , Blood parameters like blood glucose, total cholesterol, etc in two different populations?Sample Size, Power, ANOVA, t-test
202 There is an answer for this Question Site preparation for new housing developments for tracts of 40 houses is normally distributed with a mean of 250 workdays and a standard deviation of 25 workdays. a.Find the probability that the site will not be completed within 280 days b. The probability that the site is completed in less than 225 workdays or it takes more than 275 workdays95.71Z-Score
201 There is an answer for this Question Hi I am running a study comparing 3 different products on five different experimental visits. The same subjects are used for each visit and the same tests are carried out each time on all 3 products. What is the best way to radomise the presentation of the 3 products to try and reduce habituation? Many ThanksCounterbalance
200 There is an answer for this Question I've calculated the confidence intervals about a regression line. My data is log transformed and has high R-square value for what is called "power" equation in Excel. My CI's are narrow at the top of the graph and very wide near the bottom. Can I use the "standard" method used to calculate CI about a linear regression curve for the log transformed data and apply it to the power equation? My CI calculation used is CI = t*SYX*SQRT(1/n+(X-XAVG)^2/SS When I have a CI envelope that is narrow at top and very wide at the bottom of the regression line what does that mean? Interestingly, when the R-square value is low the CI plots about the regression line make a much more "palatable" envelope. This may be because both the curves generated from linear and power equations have slopes and similar r-squares.87.14
199 There is an answer for this Question A local bakery determines that the probability of a customer ordering a blueberry muffin is 50%. 5 customers come into the bakery. A. What is the probability that 3 out of the 5 order a blueberry muffin? B. Explain why this scenario would meet the criteria of a binomial distribution. A random sample of 100 students who took a statistics exam were asked their score on the exam. The mean score on the test was 50; the standard deviation was 10. The scores are normally distributed. A) What percent of the students scored below 30? B) What percent scored between 30 and 55?Binomial Probability, binomial
198 There is an answer for this Question Find the value of Z a/2 that corresponds to a level of confidence of 98.22 percent.
197 There is an answer for this Question Annual starting salaries for college graduates with degrees in business administration are generally expected to be between $30,000 and $45,000. Assume that a 95% confidence interval estimate of the population mean annual starting salary is desired. What is the planning value for the population standard deviation (0 decimals)? __________ How large a sample should be taken if the desired margin of error is as shown below (0 decimals)? a. $500? __________ b. $200? __________ c. $100? __________ d. Would you recommend trying to obtain the $100 margin of error? _________________Normally Distributed, Standard Deviation
195 There is an answer for this Question Time/CNN voter polls monitored public opinion for the presidential candidates during the 2000 presidential election campaign. One Time/CNN poll conducted by Yankelovich Partners, Inc., used a sample of 589 likely voters (Time, June 26, 2000). Assume the population proportion for a presidential candidate is p = .50. Let be the sample proportion of likely voters favoring the presidential candidate. What is E()? ____ Calculate () (to 4 decimals). ______95.71
194 There is an answer for this Question Why should you use ANOVA instead of several t tests to evaluate mean differences when an experiment consists of three or more treatment conditions?Bonferroni correction, ANOVA, Type I Error
193   How can I determine the sample size for data that is discrete but not binary?
191 There is an answer for this Question When would you use regression correlation at your place of employment, in your education, or in politics?
190 There is an answer for this Question 200 people were sampled and the following table shows the number of people with a certain average electric energy usage based upon the type of home an individual lives in: Electric Usage (in kWh) Type of Dwelling < 5,000 5,000 – 7,000 7,000 – 11,000 11,000 – 15,000 Total Single Family 15 35 65 25 140 Multi-Family 25 15 15 5 60 Total 40 50 80 30 200 a) What is the probability of selecting someone who uses between 7,000 and 11,000 kWh? b) What is the probability of randomly selecting someone who uses less than 5,000 kWh and who lives in a multi-family dwelling? c) What is the probability of selecting someone who lives in a single family dwelling or uses between 5,000 and 7,000 kWh?Addition Rule, Mutual Exclusive
189 There is an answer for this Question A sample of PVC pipes coming off a production line were tested for pipe diameter size. The statistical results (in millimeters) were: Mean 300 Median 300 Mode 300 Standard Deviation 15 Range 90 Number in Sample 100 a) According to the Normal Rule, what percent of the pipes had diameters between 285 and 315? b) What would the range of pipe diameters need to be in order to capture 95% of the pipe diameters?50Normal Rule, Normal Curve, Bell Curve, Normal Distribution
188 There is an answer for this Question How do I do a Chi-Square test on unequal sample sizes?Chi-Square, Unequal Sample Size
186 There is an answer for this Question how does altman build z-score? please send to my email the process of building this score!Altman Z-Score, Z-Score
185 There is an answer for this Question Hi I am performing a regression analysis with 3 x variables. My question is, if I have high p values (i.e. above 0.05) for each of the x coefficient but a high Adjusted R square (close to 90%), what does this imply about my equation and on my findings? Thanks!100Regression Analysis, collinearity, Correlation
183   I am trying to apply the problem discovery sample size formula to several finite populations. How should I integrate the finite population correction factor (FPC) into this formula?Problem Discovery, Finite Population
182 There is an answer for this Question When would you use a hypothesis test for the difference in two population proportions at your place of employment, in your education, or in politics?100Hypothesis Test, Two-Proportion Test
181 There is an answer for this Question What is the difference between a population standard deviation and a sample standard deviation?Standard Deviation, Degrees of Freedom
180 There is an answer for this Question How to convert a exam score (standard score) back to Percent score? e.g. Total of students 16, 71 76 56 79 74 72 68 75 77 61 81 75 70 77 77 67 65.71Standard Score, Percentile, Percent Score
177 There is an answer for this Question Find the probability that a randomly selected adult has an IQ that is less than 13084.29IQ Score, Z-Score
176 There is an answer for this Question In a 0ne-tail test (l side) with z score of 1.645, what are the percentages for critical value and non-critical value?82.86One-Tailed Area, Z-Score, Critical Value
175 There is an answer for this Question Suppose that in NY State, 35% of voters are Democrats, 30% are Republicans, and 11% are independent. You are conducting a poll by randomly calling registered voters. In your first four calls, what is the probability that you talk to: a)all Republicans? b)exactly 2 Republicans? c)no Independents? d)all Independents? e)at least one independent?4.29Probability, Multiplication Rule, Binomial Probability, Choose, binomial
173 There is an answer for this Question why can you not have a z- score equaling 0/0 ? what is problematic with calcutlating a z-score for a data set of repeated entries?100Z-Score
172 There is an answer for this Question The library is to be given 3 books as a gift. The books will be selected from a list of 18 titles. If each book selected must have a different title, how many possible selections are there?Choose, Combination
170 There is an answer for this Question If last six month average defect rate is 5% then what will be the process Zst score? 1.5 Sigma Shift, Z-Score, Z Short Term
169 There is an answer for this Question Various temperature measurements are recorded at different times for a particular city. The mean of 25C is obtained for 60 temperatures on 60 different days. Assuming that pop st/deviation is 1.5C, test the claim that the population mean is 23C. Use a 0.05 significance level. Identify the null hypothesis, alternative hypothesis, test statistic, P-value, conclusion about the null hypothesis, and final conclusion that address the original claim.Null Hypothesis , Alternative Hypothesis , t-statistic, Z-Statistic, 1-sample t-test
167 There is an answer for this Question I know that 33 is the raw score of the 85th percentile. How do I determine the mean?Percentile, Standard Deviation
166 There is an answer for this Question What is the equation to go from a Z-score to a percent? I know how to use the table but i want to know the actual formula/equation.95Newton-Raphson
164 There is an answer for this Question how to calculate one sided 95% confidence limits for a proportion.could you provide a formula Adjusted Wald, Confidence Intervals, One-Tailed Area
163 There is an answer for this Question When calculating confidence interval estimates...how is the x and standard deviation calculated?Standard Deviation, Confidence Intervals
162 There is an answer for this Question I am trying to do A/B testing onweb page displays. One is the test the other is the control. Could you help me determine the formula for sample size at a 95% confidence level? My historical Conversion Rate (success): 11% Visitors: 280 per day I would like to see a 2% improvement in my conversion rate. 94.29Confidence Intervals, Control Chart, A/B Testing, p-chart
161 There is an answer for this Question z Scores lenths are measured in centameters, does it have to be converted to a different unit of measurment? Z-Score
160 There is an answer for this Question in a sample of 1000 tv vieweres 330 watched a particlar programme. find 99 pecent confidence limits for tv viewers who watched this programmeConfidence Intervals, Adjusted Wald
159 There is an answer for this Question A parameter is a population characteristic. The numerical value of a parameter usually cannot be determined because we cannot measure all units in the population. We have to estimate the parameter using sample information. A statistic is a characteristic of a sample. A statistic estimates a parameter. To estimate the parameter, we take a random sample from the population and use the sample to calculate a sample statistic that estimates the parameter.
158 There is an answer for this Question If I have a set of values(direct measurements of dynamic deformations of a road at 100m) between 3 and~1000, how can I calculate the 2 characteristical values wich limits the interval including 85,95% of all possible measurements on this road? Using stdev and t-Student, the lower value results negative if some values are too high(all values & results MUST be positives). If the aberant values are the problem how to analyse the dataset to check wich values to reject?Monte-Carlo, Student-t, t-distribution
157 There is an answer for this Question With a z score of 1.5, what percentage often scores are above 52 and what percentage of the scores are above 60?100Z-Score
156   Could you please tell me in what situation the maentl hanszel test is more appropriate than using chi square. I believe maentl hanszel is used when a confounding variable is present thus allowing for adjustment. But when the confounding variable is taken into account after randomization of patients how is stratification performed?
155 There is an answer for this Question difference between a sample parameter ( X-bar and s ) and a proportion parameter ( p )? x-bar, Standard Deviation
154   I can do the math in all of my Probability & Stats 101 questions, but I can't tell which formula to use for what question. How can I interpret the word problems in order to know when to use which formula? Are there rules of thumb or words which will help me sort through the concepts quickly to determine which concept I need to use to answer a question? Or, can you point me to a good place to go to look at lots of problems and answers? I'm worried about my final exam in my college course. Thanks in advance. O
153 There is an answer for this Question You survey a sample of 10 college students to measure their racial prejudice using a scale of 0 (no prejudice) to 100 (extreme prejudice). Here are the scores you obtained. 10 43 30 30 45 82 12 26 24 35 Compute the mode, median, mean, and standard deviation for this sample. Is there a skew; and if so, is it positive or negative? What does this skew reveal about the dispersion in the sample. 100skew, Median
152 There is an answer for this Question If 350 respondents out of a random sample of 1,000 Americans reported that they did not trust their government, what is your estimation at a 99% confidence level of the proportion of the American population who do not trust their government?Adjusted Wald, Confidence Intervals
151 There is an answer for this Question A random sample of 25 households finds that an average of 2.3 people reside in each house (the standard deviation is 0.35). With a 95% confidence level, what is your estimation of the population average?TINV, t-statistic, t-distribution, Confidence Intervals, Standard Error of the Mean, Margin of Error
150   Exploitron, Inc. conducts a random survey of 700 of their workers and finds that the average employee earns $31,782 per year, with a standard deviation of $622. The Census reports that the average American worker makes $30,059. The CEO of Exploitron claims that his company pays their workers more than average. With a 95% confidence level, do you agree?
149 There is an answer for this Question You are interested in whether men participate more than women in political activities, so you survey 632 men and 675 women and ask them how many political events they attended within the past year. Here are your results: MEN WOMEN mean = 1.58 mean = 1.42 s.d. = 0.10 s.d. = 0.23 N=432 N=375 With 95% confidence what do you conclude?2-sample t-test, t-statistic, t-test
147 There is an answer for this Question find the midrange for the given sample data. 1.5 2.5 3.0 1.2 1.3 3.8 1.8 3.3 2.3 2.9 1.8Mid-range
146 There is an answer for this Question what is the z-score that corresponds to the 20th percentile of the normal distribution84.29Z-Score, Percentile, .20
145 There is an answer for this Question Will the t statistics calculated from 4 observations valid?88.57t-statistic, t-distribution, Small Sample
144   In a council election, 5 people are running, 3 seats available, and you want two for sure to win,but no caring who the third is. Should you only vote for the two candidates that you want and leave the third ballot blank or should you vote for the two you want and write-in a random name on the third ballot? Could that throw off the election for the other three? Would it matter statistically?
143 There is an answer for this Question how to interpret the z- score
142   Opposed to death penalty. Year 2000- 801 opposed out of 2565. Year 1993 337 opposed out of 1488. I have two samples, one is 31.2% and one is 22.6%. I am trying to calculate the 95% confidence interval in context of this situation. ALso i need the formula that is used to calculate the interval and substitute appropiate numerical values into the formula. Then with this how do i find the value of (P1 with a ^ over it-P2 with a ^ over the P)So with this how do I find the 90% confidence interval for the difference between the population proportions opposed to the death penalty in the years 2000 and 1993.
141 There is an answer for this Question whwn we say six sigma, does it mean six sigma on either side of the axis or is 3 sigma on either side44.29Six Sigma
140   Prediction of business failure using statistical methods
139   how do you calculate the appropriate analysis
138   You can win $100 if you succeed in any one of the following: 1) draw a spade from a fresh deck of cards; 2) draw a heart from a fresh deck of cards; or 3) flip a fair coin and it comes up tails. What is the probability that you will win $100? What is the probability that you will not win $100?
137 There is an answer for this Question What score would Sandra need to beat 91 percent of her mathematics class? The mean score was 73, and the standard deviation was 12.96.43Z-Score
136   Ran parts and found 1% defective(1 out of 100). Made a change to the process and want to rerun parts. How many parts do we need to check (and find 0% defective) for a 90% confidence factor that there are not any defects in the rerun? Process Sigma, DPMO
135 There is an answer for this Question I am conducting a ring test where 6 laboratories were asked to measure protein levels in the same flour sample. I then calculated the z score for each of their results ... z score obtined ranged from 0 to 1.7. Does the higher z score indicate that the laboratories are too far away from the norm and that they need to review their process or their staff (assuming that they are using the same test procedure)??Z-Score
134   In one region, the september energy consumption levels for single-family homes are found to be normally distributed with a mean of 1050kWh and a standard deviation of 218kWh. Find p45, which is the consumption level separating the bottom 45% from the top 55%.Z-Score
133   When number of Passed is half of total Tested, why all points estimates are 0.50. TkStandard Score
132 There is an answer for this Question why use 6sigma instead of 5 or 4sigma in calculating process capability100Six Sigma, DPMO, Process Sigma, Sigma Level
131   which statistic technique can i use.. when i apply three treatment(treatment 1, treatment2, treatment3)on 2 dependent variable?(i applied 3 treatments consecutively and i checked effect of them on 2 dependents variable. can i apply repeated measure of anove..
130   what is the value of 1sigma 2sigma 3sigma 4sigma 5sigma 6sigmaSix Sigma
129   Hi when we have several criteria with different scale, for ranking can we add values after standardization? for exaample for ranking websites we have number of visitors and page load time and size and... if we standardized values by z, then can we add the values for ranking?
128 There is an answer for this Question what is the value of z score required for a 70% confidence interval?50Z-Score, Confidence Intervals
127   can anyone explain? Age so individuals in a certain population are normally distributed with a mean of 55 and standard deviation of 10 years. What age reange would make up the youngest 5% of the population?
126   what is the distinction between a qualitative and a qualitative measure?
125 There is an answer for this Question When testing two populations with small sample sizes, do both sample sizes have to be identical? Why or why not?Unequal Sample Size
124 There is an answer for this Question What constitutes a small sample size in a test of two populations? t-distribution, Z-Statistic, Small Sample
123   How does a non-parametric business scenario differ from a parametric business scenario?
122   When would you use a hypothesis test for the difference in two population proportions at your place of employment?
121   What is the differences among a proportion, a percentage, and a ratio?
120 There is an answer for this Question What statistics test should I be using when I am assessing whether subjects were able to complete a task (i.e. Yes/No nominal data) before instructions, after instructions and then again after a demo (i.e. 3 data sets). It is the same subjects in each group. Which test should I use when comparing four different conditions?
119 There is an answer for this Question Is is possible to modify a semantic differential scale into a 10-point scale? If so, should the data be treated as ordinal or interval? Bell Curve, ANOVA, Ordinal, Interval
117   What is the significance of the picture at the top of the t-table? What is the difference between a sample parameter (X-bar and s) and a proportion parameter (n)?
116   Hi. I'm going to run a nested model in logistic regression. I have a dependent variable (nest) and I have two sexes (male/female). I can not run this model with two sexes, so I guess I have to split them up or it there some way to run the analysis and include both sexes?
114 There is an answer for this Question The mean on this test is 3.5 with a standard deviation of .5. Billy scores 5. What is the standard score?100Standard Score, Z-Score
113   How do you find the value of r?
112   getting the formular for confindence interval
111   Expected Project duration:25 days Probability for 27 days Standard deviation :5.656
110   If I have unnormal data with n=15, and there are 2 samples. What test do I use? How do I make the data normal if the samples contain zero, b/c it's measuring time?
109   A director of a social agency is planning to hire temporaty staff to assist with intake. In making plans, the director needs to know whether there is any difference in the use of he agency at different seasons of the year. Last year there were 28 new clients in the winter, 33 in the spring, 16 in the summer, and 51 in the fall. On the basis of last year's data, should the director conclude that season make a difference? (use the .05level.) Explain your answer to a person wo has never taken a course in statistics. (this problem is like the Harter et al. example in which you are doing a chi square for a single nominal variable. It is not a chi-square test for independence and does not involve any contingency tables.
108   Compute a chi-square test for goodness of fit for each of the following, using the .05 level for each. In each problem, the expected distribution is equal frequencies in each category. A. 5 10 5 B. 10 15 10 C. 10 20 10 D. 5 15 5
107   Suppose a candidate running for sheriff claims that she will reduce the average of emergency response to less than 30 minutes. (30 minutes is thought to be the average response time with the current sheriff.)there are no past records, so the actual standard deviation of such response times cannot be determined. Thanks to this campaign, she is elected sheriff, and careful records are now kept. The response times for the first month are 26, 30, 28, 29, 25, 28, 32, 35, 24 and 23 min. Using the .05 significance level, did she keep her promise? A. Go through the five steps of hypothesis testing. B. Illustrate your answer with a histogram of the sample's scores and sketches of the population distribution and the distribution of means, showing the t score and cutoff points for significance. C. Explain your answer to someone who has never taken a course in statistics.
106   suppose that the scores of architects on a particular creativity test are normally distributed. What percentage of architects have Z scores?
105 There is an answer for this Question For large correlations, the SAS program simply states that p < .0001. But to conduct a meta-analysis I need to know the exact p values for large correlations. Where is a table of r to p for various sample sizes (less than 100)? Or can I instruct SAS to calculate the exact p to 8 decimal places?
104   Trimmed mean, 80% trimmed mean = ? was a question on a homework assignment. When I read my notes the teacher had written 10 values, then eliminated the lowest and highest values,then took the mean of the remaining 8 values. Wouldn't that make it a 10% trimmed mean? or is it 80% trimmed mean, because 8 numbers remained after truncating 2 values? Thanks, Liz I am confused.
103   What is the Standard Deviation of a z-score?
102   How can a t test be employed in hypothesis testing by the use of directional vs. nondirectional hypotheses?
101   When is using