An insurance company offers its policyholders a number of different premium payment options. For a randomly selected policyholder, let X be the number of months between successive payments. The PMF of X is given as follows: x 2 4 6 P(x) 0.3 0.3 0.4

4-1 (1 mark) Calculate E[X(X-1)]. 4-2 (1 mark) Determine the CDF (Cumulative Distribution Function) of X.