A major retail clothing store is interested in estimating the difference in mean monthly purchases by customers who use the store's in-house credit card versus using a Visa, Mastercard, or one of the other major credit cards. To do this, it has randomly selected a sample of customers who have made one or more purchases with each of the types of credit cards. The following represents the results of the sampling:
In-House Credit Card National Credit Card
Sample Size: 86 113
Mean Monthly Purchases: $45.67 $39.87
Standard Deviation: $10.90 $12.47
Given this information, which of the following statements is true?
Question 1 options:
If either of the sample sizes is increased, the resulting confidence interval will have a smaller margin of error.
If the confidence level were changed from 95 percent to 90 percent, the margin of error in the estimate would be reduced.
Neither A nor B are true.
Both A and B are true.
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