9.3 The number of breakdowns per week for a certain minicomputer is a random variable X having a Poisson distribution with mean . A random sample X1, . . . ,Xn of observations on the number of breakdowns per week is available.

a Find an unbiased estimator of .
b The weekly cost of repairing these breakdowns is Show that c Find an unbiased estimator of E(C) that makes use of the entire sample, X1,…,Xn.