Question

Suppose 5 men and 7 women are on a crowded elevator. At the next floor, four people get off the elevator. Find the probability that three are women.

0.010

0.354

0.424

0.25

Answer 1

• B. 0.354

Explanation:

Combination of 4 out of 5 + 7 = 12 is:

• 12C4 = 12!/8!4! = 495

Combination of 1 man and 3 women is:

• 5C1*7C3 = 5*7!/4!3! = 5*35 = 175

Required probability:

• P(3W) = 175/495 ≈ 0.353

Correct choice is B