# Confidence interval for the population mean

A corporation that maintains a large fleet of company cars for the use of its sales staff is interested in the mean distance driven monthly per sales person. The following table gives the monthly distances in miles driven by a random sample of 20 sales persons

2314, 2102, 1999, 1951, 2602, 2468, 1881, 2381, 2230, 1966, 2246, 2601, 2531, 2560, 2660, 2022, 2319, 2106, 2410, 2034

Based on this sample, find a 99% confidence interval for the mean number of miles driven monthly by members of the sales staff, assuming that monthly driving distances are normally distributed. Then complete the table below.

Carry your intermediate computations to at least three decimal places. Round your answers to one decimal place

What is the lower limit of the confidence interval?

What is the upper limit of the confidence interval?

https://brainmass.com/statistics/confidence-interval/confidence-interval-population-mean-224888

#### Solution Preview

Confidence interval for the population mean: Use of the t distribution

A corporation that maintains a large fleet of company cars for the use of its sales staff is interested in the mean distance driven monthly per sales person. The following table gives the monthly distances in miles driven by a random sample of 20 sales persons

2314, 2102, 1999, 1951, 2602, 2468, 1881, 2381, 2230, 1966, 2246, 2601, 2531, 2560, 2660, 2022, 2319, 2106, 2410, 2034 (sample also copied from excel)

Based on this sample, find a 99% confidence interval for the mean number of miles driven monthly by members of the sales staff, assuming that monthly driving distances are normally distributed. Then complete the table below.

...

#### Solution Summary

The expert calculates the confidence interval for the population mean, using the t distribution.