The tread life of tires mounted on light-duty trucks follows the normal probability distribution with a mean of 60,000 miles and a 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) 4000
D) Cannot be determineD.

Question

Quizplus · Accepted Answer

The standard error of the mean is calculated using the formula SE = σ/√n, where σ is the standard deviation and n is the sample size. Therefore, SE = 4000/√40 = 632.46. This means that if we were to repeat the sampling process multiple times, the mean tread life of the tires would vary within ±632.46 of the population mean of 60,000 miles.

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