# Confidence interval estimate for the population mean

An auditor for a large oil corporation has taken a random sample of monthly credit card charges for 32 individual (non-corporate) accounts. She found a mean of $81.76. Assume that the population standard deviation is 48.2. A 98% confidence interval estimate for the population mean of individual credit card charges would be.

a. 81.76 ± 19.89

b. 81.76 ± 16.72

c. 81.76 ± 112.94

d. 81.76 ± 22.0

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#### Solution Preview

An auditor for a large oil corporation has taken a random sample of monthly credit card charges for 32 individual (non-corporate) accounts. She found a mean of $81.76. Assume that the population standard deviation is 48.2. A 98% confidence interval estimate for the population mean of individual credit card ...

#### Solution Summary

Calculates a 98% confidence interval estimate for the population mean of individual credit card charges.