Question: Mactronics produces industrial robots. Each robot contains a part with a lifetime of five years at most, and at least one year. Lifetimes between one and five years are equally likely. If the part fails during operation, replacement costs are estimated to be $400, whereas the part can be replaced before failure for $50. When should the part be replaced?
[Hint: The lifetime distribution is uniform on 1, 2, 3, 4, 5-. Assuming discrete variables, this means that f(x) = 1/5 for x = 1, 2, . . . , 5.]