Work Shown - A market researcher

A market researcher plans to sample sales receipts at a natural food store to estimate the average size (in dollars) of a customer purchase. Previous analysis suggests that the standard deviation of the purchase amount is approximately $25.

In order to calculate a 95% confidence interval of total width less than $5, how many sales records should the researcher include in her sample?

E) 97.

F) 271.

G) 385.

H) The answer can not be determined from the information provided.

 
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