Question

A random sample of 10 drivers reported the below average mileage in the city for their...

A random sample of 10 drivers reported the below average mileage in the city for their cars.

18, 21, 24, 25, 25, 25, 25, 26, 29, & 31

The mean of the sample is 24.9 miles per gallon, with an associated standard deviation of about 3.6.

Find the 95% confidence interval for the average mileage of the cars for all of the drivers in the class. Assume all normality conditions apply.

Determine the approximate sample size needed to estimate the mean of the population with 90% confidence, if the desired margin of error for that estimate is 15. The population standard deviation is 100.

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