pls explain.thanks

(8 points) Let the random variable X be the number of rooms in a randomly chosen owner-occupied housing unit in a certain city. The probability distribution function for the units is given below, X 3 4 5 10 Pr(X) 0.07 0.22 0.39 0.2 0.03 0.05 0.03 a. Find Pr(X = 10), the probability of randomly choosing a unit with 10 rooms. b. Find Pr(4