The peak ground acceleration (PGA; in g) at a distance R (in km) from the epicenter of an earthquake with Richter magnitude M can be estimated by 0.8M PGA = 1.25- e (R+25) Assume that M and R are independent random variables, uniformly distributed on the intervals 5.5 < m < 6.5 and 20 < r < 30, respectively. Compute E[PGA], Var[PGA] and COV[PGA] .