Question

The bookstore offers a statistics textbook for $200 and a book supplement for $50. From past experience, they know about 25% of statistics students just buy the textbook while 60% buy both the textbook and supplement.

a) Let random variable X represent the revenue from a single student. Write out the probability distribution of X (You don't need to draw the table. Just list the possible values and their corresponding probabilities in two separate lines). Assume no students buy the supplement without the textbook.

b) Compute the expected value and the standard deviation of X.

Answer 1