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C. Suppose a random sample of customer order totals has an average of k78.25 and a population standard deviation of k22.50. (i) Calculate a 90% confidence interval for the mean, given a sample size of 40. (ii) Calculate a 90% confidence interval for the mean, given a sample of 75 orders. (iii) Explain the difference in the 90% confidence intervals calculated in the problems (i) and (ii).

C. Suppose a random sample of customer order totals has an average of k78.25 and a population standard deviation of k22.50. (i) Calculate a 90% confidence interval for the mean, given a sample size of 40. (ii) Calculate a 90% confidence interval for the mean, given a sample of 75 orders. (iii) Explain the difference in the 90% confidence intervals calculated in the problems (i) and (ii).

Glencoe Algebra 1, Student Edition, 9780079039897, 0079039898, 2018
Glencoe Algebra 1, Student Edition, 9780079039897, 0079039898, 2018
18th Edition
ISBN:9780079039897
Author:Carter
Publisher:Carter
Chapter10: Statistics
Section10.4: Distributions Of Data
Problem 19PFA
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QUESTION FIVE A. Define sampling error B. The following are ages of 10 customers in a retail store: Customer age 36 29 55 22 34 67 30 41 35 If the first three customers in the table are chosen to estimate the average age of all 10 customers, what is the sampling error? C. Suppose a random sample of customer order totals has an average of k78.25 and a population standard deviation of k22.50. (i) Calculate a 90% confidence interval for the mean, given a sample size of 40. (ii) Calculate a 90% confidence interval for the mean, given a sample of 75 orders. (iii) Explain the difference in the 90% confidence intervals calculated in the problems (i) and (ii). D. Suppose a certain company claims that the average time a customer waits on hold is less than 5 minutes. A sample of 35 customers has an average wait time of 4.78 minutes. Assume the population standard deviation for wait time is 4.8 minutes. (i) Test the company's claim at a=0.05 significance level by comparing the calculated Z-score to the critical z-score. (ii) Verify your answer to problem (i) by comparing the sample mean X-4.78 to the critical sample mean Xc. (iii) Verify your answer to problem (i) by comparing the p-value to the level of significance a=0.05. 21
Transcribed Image Text:QUESTION FIVE A. Define sampling error B. The following are ages of 10 customers in a retail store: Customer age 36 29 55 22 34 67 30 41 35 If the first three customers in the table are chosen to estimate the average age of all 10 customers, what is the sampling error? C. Suppose a random sample of customer order totals has an average of k78.25 and a population standard deviation of k22.50. (i) Calculate a 90% confidence interval for the mean, given a sample size of 40. (ii) Calculate a 90% confidence interval for the mean, given a sample of 75 orders. (iii) Explain the difference in the 90% confidence intervals calculated in the problems (i) and (ii). D. Suppose a certain company claims that the average time a customer waits on hold is less than 5 minutes. A sample of 35 customers has an average wait time of 4.78 minutes. Assume the population standard deviation for wait time is 4.8 minutes. (i) Test the company's claim at a=0.05 significance level by comparing the calculated Z-score to the critical z-score. (ii) Verify your answer to problem (i) by comparing the sample mean X-4.78 to the critical sample mean Xc. (iii) Verify your answer to problem (i) by comparing the p-value to the level of significance a=0.05. 21
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