Question

Suppose that the company warrants the tires for 60,000 miles. What proportion of the tires will last 60,000 miles?

A) 0%
B) 25%
C) 50%
D) 100%

Answer 1

The proportion of tires that will last 60,000 miles is 100%.

Step-by-step explanation:

To find the proportion of tires that will last 60,000 miles, we need to determine how many standard deviations above the mean 60,000 miles is. The mean lifespan of the tires is 46,500 miles with a standard deviation of 9,800 miles. Using this information, we can calculate the z-score.

z = (x - mean) / standard deviation

z = (60,000 - 46,500) / 9,800 = 1.38

Looking up the z-score in a standard normal distribution table, we find that the proportion of tires that will last 60,000 miles is approximately 91.92%. Therefore, the answer is D) 100%.