# Confidence interval for the population mean

Families USA, a monthly magazine that discusses issues related to health and health costs, surveyed 20 of its subscribers. It found that the annual health insurance premiums for a family with coverage through an employer averaged $10,979. The standard deviation of the sample was $1,000.

a. Based on this sample information, develop a 90 percent confidence interval for the population mean yearly premium.

b. How large a sample is needed to find the population mean within $250 at 99 percent confidence?

https://brainmass.com/statistics/confidence-interval/confidence-interval-for-the-population-mean-229997

#### Solution Summary

This solution finds a 90 percent confidence interval for the population mean and shows how to find the sample size necessary to be 99 percent confident that the margin of error is within a stated bound.

$2.19