Q:

The tread life of a particular brand of tire is a random variable best described by a normal distribution with a mean of 60,000 miles and a standard deviation of 1000 miles. What warranty should the company use if they want 96% of the tires to outlast the warranty? 59,000 miles 58,250 miles 61,000 miles 61,750 miles

Accepted Solution

A:
Answer: 61,750 milesStep-by-step explanation:Given : The p-value of the tires to outlast the warranty = 0.96The probability that corresponds to 0.96 from a Normal distribution table is 1.75. Mean : [tex]\mu=60,000\text{ miles}[/tex]Standard deviation : [tex]\sigma=1000\text{ miles}[/tex]The formula for z-score is given by Β : -[tex]z=\dfrac{x-\mu}{\sigma}\\\\\Rightarrow\ 1.75=\dfrac{x-60000}{1000}\\\\\Rightarrow\ x-60000=1750\\\\\Rightarrow\ x=61750[/tex]Hence, the tread life of tire should be 61,750 miles if they want 96% of the tires to outlast the warranty.