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    Point Estimate and Confidence Interval

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    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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    Solution Preview

    Please see attached file:
    Confidence interval for difference between means (large sample size)
    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

    Data

    Sample 1: Store's Card
    Mean of sample 1= M1 = $140
    Standard deviation of sample 1= s1 = $10 ...

    Solution Summary

    Calculates the point estimate and confidence interval for the difference between the mean purchases of the users of the two credit cards.

    $2.19

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