PLEASE SHOW WORK

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

Sample size

64

Sample mean

$140

Population standard deviation

$10

Major Credit Card

Sample size

49

Sample mean

$125

Population standard deviation

$8

a. At 95% confidence, the margin of error is how much?

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

PLEASE SHOW WORK