A box contains 3 blue marbles, 4 red, 6 green marbles and 2 yellow marbles. If four marbles are picked at random, what is the probability that none is blue?
Q1. A box contains 3 blue marbles, 4 red, 6 green marbles and 2 yellow marbles. If four marbles are picked at random, what is the probability that none is blue?
Answer: 33/91
Explanation: Non-blue marbles = 12; P(none blue) = C(12,4)/C(15,4) = 495/1365 = 33/91.