Suppose that a company claims that its batteries last 240 hours on average.

It took many large samples, and each time the mean number of hours was

outside the 95% confidence interval. Based on this information alone, which

of the following is probably not the mean number of hours that the company's

batteries last?

A. 235

B. 240

C. 230

D. 225

Question

Mac

Mathematics

6 May, 11:29

Suppose that a company claims that its batteries last 240 hours on average.

It took many large samples, and each time the mean number of hours was

outside the 95% confidence interval. Based on this information alone, which

of the following is probably not the mean number of hours that the company's

batteries last?

A. 235

B. 240

C. 230

D. 225

+5

Answers (2)

Know the Answer?

Peep · Answer 1

The correct option is D.

Confidence interval is used to express the degree of uncertainty associated with a sample statistic.

The confidence interval is calculated as,

The value of z score at 95% confidence interval is 1.96.

The confidence interval for given information is

It is given that in each time of sampling the mean number of hours was outside the 95% confidence interval. It means σ can not be zero.

It means the mean number of hours that the company's batteries last will be either below or above 245.

Therefore, the value can be anything, but not 245. The correct option is D.