Refer to Exercise 4.28. (a) Assign probabilities to the elementary outcomes. (b) Find P (A) and P (B) . Data from Exercise 4.28: A local bookstore intended to award three gift certificates in the amounts $100, $50, and $25 to the first, second, and third customer to identify a mystery author. Unfortunately, a careless clerk in charge of mailing forgot the order and just randomly placed the gift certificates in the already addressed envelopes.