Statistics for Business: Decision Making and Analysis, 3rd Edition

1. ... publicity event, the probability of a bestseller is 0.25. The probability of a major event is 0.40.

   1. Represent the three probabilities given in this question as probabilities of events, such as P(B) = 0.10. You do the other two.⁷

      ⁷ P(B) = 0.10, P(M) = 0.40, P(B|M) = 0.25.

   2. Are bestselling product launches independent of major events?⁸

      ⁸ No, dependent. P(B) ≠ P(B|M).

   3. What is the probability of a bestselling product and a major publicity event?⁹

      ⁹ P(B and M) = P(B|M) × P(M) = 0.25 × 0.4 = 0.1.

Order Matters

The order in which events are listed does not matter in unions or intersections. The union A or B is the same as the union B or A, and the intersection A and B is the same as B and A. For conditional probabilities, however, order matters. The conditional ...