74. Let X
the time (in 101 weeks) from shipment of a defective product until the customer returns the product. Suppose that the minimum return time is
3.5 and that the excess X  3.5 over the minimum has a Weibull distribution with parameters 
2 and

1.5 (see the Industrial Quality Control article referenced in Example 4.26).

a. What is the cdf of X?

b. What are the expected return time and variance of return time? [Hint: First obtain E(X  3.5) and V(X  3.5).]

c. Compute P(X 5).

d. Compute P(5  X  8).