Estimation:

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

b) At 95% confidence, the margin of error is

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

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...Sample size of sample 1= n1 = 64

Sample 2: Major Credit Card
Mean of sample 2= M2 = $125
Standard deviation of sample 2= s2 = $8
Sample size of sample 2= n2 = 49

Confidence level= 95%
Significance level=100%-Confidence level= 5% = 100%-95.%

a)A point estimate for the difference between the mean purchases of the users of the two credit cards is

Sample 1: Sample 2:
Store's Card Major Credit Card
Mean =M = $140 $125
Standard deviation =s= $10 $8
Sample size=n= 64 49

Difference of means (M1-M2)= $15.00 ...