5. Let X be a discrete random variable with the following CDF

PX(k) ={ 0, for x < 1; 0.2, for 1 x < 0; 0.5, for 0 x < 2; 0.6, for 2 x < 5; 1, for x 5}

(a) Find the PMF of X.

(b) Plot the PMF of X.