In a sample of credit card holders the mean monthly value of credit card purchas
ID: 3241741 • Letter: I
Question
In a sample of credit card holders the mean monthly value of credit card purchases was exist 262 and the sample variance was 72 (exist squared). Assume that the population distribution is normal. Answer the following, rounding your answers to two decimal places where appropriate. Suppose the sample results were obtained from a random sample of 14 credit card holders. Find a 95% confidence interval for the mean monthly value of credit card purchases of all card holders. (_____, ______) Suppose the sample results were obtained from a random sample of 25 credit card holders. Find a 95% confidence interval for the mean monthly value of credit card purchases of all card holders. (_____, _____) Before you answer (b) consider whether the confidence interval will be wider than or narrower than the confidence interval found for (a). Then check that your answer verifies this.Explanation / Answer
Mean is 262 and SD is sqrt(72)=8.485. For 95% confidence, z value is 1.96
a) n=14, thus the lower limit is 262-1.96*8.485/sqrt(14)=257.55 and upper limit is 262+1.96*8.485/sqrt(14)=266.44
b)n=25, thus the lower limit is 262-1.96*8.485/sqrt(25)=258.67 and upper limit is 262-1.96*8.485/sqrt(25)=265.326
Related Questions
Hire Me For All Your Tutoring Needs
Integrity-first tutoring: clear explanations, guidance, and feedback.
Drop an Email at
drjack9650@gmail.com
drjack9650@gmail.com
Navigate
Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.