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).
MATLAB: An Introduction with Applications
6th Edition
ISBN:9781119256830
Author:Amos Gilat
Publisher:Amos Gilat
Chapter1: Starting With Matlab
Section: Chapter Questions
Problem 1P
Related questions
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100%
Answer PArt C
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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