Question

A company claims that the average lifespan of a bicycle tire that they manufacture is 1200 miles. You randomly and independently collect a sample of 31 of these tires and find that the average distance these tires lasted was 1125.7 miles, with a standard deviation of 275 miles.

A 90% confidence interval for the population mean lifetime of these tires is (1041.9, 1209.5).

Select all true statements.

Group of answer choices

The confidence interval indicates that the company's claim that their tires last 1200 miles is ok.

The confidence interval indicates that the actual life of their tires is less than 1200 miles.

A 95% confidence interval calculated from the same data might not contain 1200.

One interpretation of this interval is "I'm 90% confident that the average lifespan of these tires is between 1041.9 miles and 1209.5 miles."

This confidence interval indicates the average life of the company's tires is probably less than 1250 miles.

It's possible that these tires actually last an average of 1300 miles.

Answer 1

The 90% confidence interval for the population mean lifetime of these tires is (1041.9,1209.5)

The true statements will be as follows:

The confidence interval indicates that the company's claim that their tires last 1200 miles is ok.

One interpretation of this interval is "I'm 90% confident that the average lifespan of these tires is between 1041.9 miles and 1209.5 miles."

This confidence interval indicates the average life of the company's tires is probably less than 1250 miles.