The management of a department store is interested in estimating the difference between the mean credit purchases of customers using the store's credit card versus those customers using a national major credit card. You are given the following information. Store's Card

Major Credit Card

Sample size
64

49

Sample mean
$140

$125

Population standard deviation
$10

$8



A point estimate for the difference between the mean purchases of all users of the two credit cards is?

At 95% confidence, the margin of error is?

A 95% confidence interval estimate for the difference between the average purchases of all customers using the two different credit cards is?