= 1 0.08 – = 0.92 2-25. a. Probability = over = 0.2. P(K M) b. Probability = over = 0.4. P(K MB) c. Probability = [P(K over and over or M) P(MB K)] [P(K over and over MB) P(M K)] = (0.2)(0.6) + (0.4)(0.8) = 0.12 + 0.32 = 0.44 d. Probability = [P(K over and over MB) P(K M)] = (0.4)(0.2) = 0.08 e. Probability = over and over P(MB K) P(M K) = (0.6)(0.8) = 0.48 f. No. They do not appear to be a very good team. 2-26. The probability of Dick hitting the bull’s-eye: = 0.90 P(D) The probability of Sally hitting the bull’s-eye: = 0.95 P(S) a. The probability of either Dick or Sally hitting the bull’s-eye: or = + P(D S) P(D) P(S) P(D)P(S) – = 0.90 + 0.95 (0.90)(0.95) – = 0.995 b. and = P(D S) P(D)P(S) = (0.9)(0.95) = 0.855 c. It was assumed that the events are independent. This assumption to be justified. Dick’s performance shouldn’t influence Sally’s performance. In the sample of 1,000 people, 650 people were from Laketown and 350 from River City. 2-27. Thirteen of those with cancer were from Laketown. Six of those with cancer were from River City.
= 1 – 0.08 = 0.92 2-25. a. Probability = P(K over M) = 0.2. b. Probability = P(K over MB) = 0.4. c. Probability = [P(K over M) and P(MB over K)] or [P(K over MB) and P(M over K)] = (0.2)(0.6) + (0.4)(0.8) = 0.12 + 0.32 = 0.44 d. Probability = [P(K over MB) and P(K over M)] = (0.4)(0.2) = 0.08 e. Probability = P(MB over K) and P(M over K) = (0.6)(0.8) = 0.48 f. No. They do not appear to be a very good team. 2-26. The probability of Dick hitting the bull’s-eye: P(D) = 0.90 The probability of Sally hitting the bull’s-eye: P(S) = 0.95 a. The probability of either Dick or Sally hitting the bull’s-eye: P(D or S) = P(D) + P(S) – P(D)P(S) = 0.90 + 0.95 – (0.90)(0.95) = 0.995 b. P(D and S) = P(D)P(S) = (0.9)(0.95) = 0.855 c. It was assumed that the events are independent. This assumption to be justified. Dick’s performance shouldn’t influence Sally’s performance. 2-27. In the sample of 1,000 people, 650 people were from Laketown and 350 from River City. Thirteen of those with cancer were from Laketown. Six of those with cancer were from River City.