# Manager's sample of 25 delivery trucks. Confidence interval

A delivery truck manager takes a sample of 25 delivery trucks and calculates the sample mean and deviation for the cost of operation. A 95% confidence interval for the mean cost is constructed and found to be $253 to $320. He reasons that this interval contains the mean operating cost for the fleet of delivery trucks since the sample mean is contained in the interval.

a. Do you agree with his reasoning?

b. How would you interpret this confidence interval?

c. Is this an appropriate use of a confidence interval?

https://brainmass.com/statistics/confidence-interval/confidence-interval-problem-delivery-truck-manager-example-338501

#### Solution Preview

A delivery truck manager takes a sample of 25 delivery trucks and calculates the sample mean and deviation for the cost of operation. A 95% confidence interval for the mean cost is constructed and found to be $253 to $320. He reasons that this interval contains the mean operating cost for the fleet of delivery trucks since the sample mean is contained in the interval.

a. Do you agree with his reasoning?

No. 95% confidence interval means that if we take 100 such samples and construct the ...

#### Solution Summary

This solution discusses the confidence interval used by the delivery truck manager.