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

Multiple Choice

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 you bought a set of four tires; what is the likelihood the mean tire life of these four tires is more than 66,000 miles?

A) 0.0013
B) 0.9987
C) 0.4987
D) 0.9544