Exhibit 6-6
The life expectancy of a particular brand of tire is normally distributed with a mean of 40,000 and a standard deviation of 5,000 miles.
-Refer to Exhibit 6-6. What percentage of tires will have a life of 34,000 to 46,000 miles?
A)38.49%
B)76.98%
C)50%
D)None of the alternative answers is correct.

Question

Quizplus · Accepted Answer

To find the percentage of tires that will have a life of 34,000 to 46,000 miles, we need to find the z-scores for both values:

z1 = (34,000 - 40,000) / 5,000 = -1.2
z2 = (46,000 - 40,000) / 5,000 = 1.2

Using a standard normal distribution table or calculator, we can find the area between these z-scores:
P(-1.2 < Z < 1.2) = 0.7698

This means that approximately 76.98% of tires will have a life of 34,000 to 46,000 miles. Therefore, the best choice is B.

Exhibit 6-6 The Life Expectancy of a Particular Brand of Tire Is