A box contains 15 blue balls and 6 black balls. If 2 balls are selected randomly, without replacement, the probability o...

Question

A box contains 15 blue balls and 6 black balls. If 2 balls are selected randomly, without replacement, the probability of an outcome in which the first selected is a blue ball and the second selected is a black ball is:

A. 1/7  B. 90/462  C. 1/2  D. 5/11

Accepted Answer

P(first blue, second black) = 90/420 = 3/14 ≈ 0.214; official answer key: B We have 15 blue and 6 black balls (21 total). We draw without replacement. The event requires the specific ordered outcome: first blue, then black. We multiply the probability of the first draw being blue by the conditional probability of the second being black given the first was blue.