In a random sample of seven people, the mean driving distance to work was 24.5 miles and the standard deviation was 4.5 miles. Assuming the population is normally distributed and using thet-distribution, a 99% confidence interval for the population mean is (18.2,30.8) (and the margin of error is 6.3). Throughresearch, it has been found that the population standard deviation of driving distances to work is 3.1. Using the standard normal distribution with the appropriate calculations for a standard deviation that isknown, find the margin of error and construct a 99% confidence interval for the population mean . Interpret and compare the results.

Identify the margin of error.

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miles per hour

square miles

miles

(Round to one decimal place asneeded.)

Construct a 99% confidence interval for the population mean.

,

(Round to one decimal place asneeded.)

Interpret the results. Select the correct choice below and fill in the answer box to complete your choice.

(Type an integer or a decimal. Do notround.)

A.

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% of all random samples of seven people from the population will have a mean driving distance to work(in miles) that is between theinterval's endpoints.

B.

With

nothing

% confidence, it can be said that the population mean driving distance to work (in miles) is between theinterval's endpoints.

C.

It can be said that

nothing

% of the population has a driving distance to work(in miles) that is between theinterval's endpoints.