Let X denote the number of hours you study during a randomly selected school day. The probability that X can take the values x, has the following where k is come unknown constant.

What is the probability that you study at least two hours?

0.75 0.25 0.5 0.67

0.75

P(at least two hours) = P(X>=2)  P(X>=2) = P(X=2) + P(X=3) + P(X=4)               = 2k + 2k + k = 5k = 5(0.15)               =  0.75