The tread life of tires mounted on light-duty trucks follows the normal probability distribution with a population mean of 60,000 miles and a population standard deviation of 4,000 miles. Suppose we select a sample of 40 tires and use a simulator to determine the tread life. What is the standard error of the mean?
A)632.46
B)40
C)4,000
D)Cannot be determined.

Question

Quizplus · Accepted Answer

The formula for standard error of the mean is:
Standard error of the mean = population standard deviation / square root of sample size
Thus, standard error of the mean = 4000 / sqrt(40) = 632.46. Therefore, the answer is (A).

The Tread Life of Tires Mounted on Light-Duty Trucks Follows