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?