On hot, sunny, summer days, Jane rents inner tubes by the river that runs through her town. Based on her past experience, she has assigned the following probability distribution to the number of tubes she will rent on a randomly selected day.

(a) Find P(X = 75).
(b) Find P(X ≤ 75).
(c) Find P(X > 50).
(d) Find P(X < 100).
(e) Which of the probability expressions in parts (a)–(d) is a value of the CDF?

X 25 50 75 100 Total
P(X) .20 .40 .30 .10 1.00