The waiting time, in minutes, between successive speeders spotted by a radar unit is a continuous random variable X in R with cumulative distribution function F(x) = { 0 if x <= 2, 1 - 16/x^4 if x >= 2. (a) Find the probability density function of X. (b) Find the probability that the waiting time between successive speeders is more than 4 minutes but less than 8 minutes (i) using the cumulative distribution function of X, (ii) using the probability density function of X. (c) Find the expected waiting time between successive speeders.