The top selling Red and Voss tire is rated 70,000 miles means nothing. In fact, the distance the tires can run until they wear out is a normally distributed random variable with a mean of 82,000 miles and a standard deviation of 6,400.

Question

a. What is the probability that a tire wears out before 70,000 miles.

b. What is the probability that a tire last more than 100,000 miles?

Answer 1

Please use the same name for your posts. Karen, Sandra, Joi.

Answer 2

X~N(82000,6400^2)
a) P(X<70000)=P((X-82000)/6400<(70000-82000¡­ Z-table=0.0303964
P(X<70000)=0.0303964

b) P(X>100000)=P(Z>2.8125)=0.0024579

Answer 3

The top-selling Amar tire is rated 70,000 KMs, which means nothing. In fact, the distance the tires can run until they wear out is a normally distributed random variable with a mean of 82,000 KMs and a standard deviation of 6,400 KMs.

What is the probability that a tire wears out before 70,000 KMs? What is the probability that a tire lasts more than 100,000 KMs?

Note: You may use Z-table for this