Question

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

1. Do you agree with his reasoning?
2. How would you interpret this confidence interval?
3. Is this an appropriate use of a confidence interval?

Answer 1

ANSWER:

Required information is given by

sample size =25

and , confidence interval =95%

1.)

No. The sample  mean is constantly contained inside the confidence interval (it is the midpoint) paying little respect to significance.

2.)

The interval says that with 95% certainty, the true estimation of mean operating cost lies somewhere in the range of 253 and 320. As it were, there is a 95% shot that the interval contains the true mean working expense.

3.)

No. Generally, one uses such thinking for a distinction in methods or extents. On the off chance that the interim does not contain 0 (i.e, there is a distinction), at that point the methods are significantly in an unexpected way.