The average number of miles (in thousands) that a car's tire will function before needing replacement is 71 and the standard deviation is 20. Suppose that 15 randomly selected tires are
tested. Round all answers to 4 decimal places where possible and assume a normal distribution,
a. What is the distribution of X? X-NO
b. What is the distribution of 22 - NO
c. If a randomly selected individual tire is tested, find the probability that the number of miles (in
thousands) before it will need replacement is between 64.1 and 70.
d. For the 15 tires tested, find the probability that the average miles (in thousands) before need
of replacement is between 64.1 and 70.
e. For part d), is the assumption that the distribution is normal necessary? No Yes