Question

A jar contains 38 marbles. It has 10 red, 22 black, and 6 green marbles. Two marbles are drawn; the first is not returned before the second one is drawn. What is the probability that both marbles are black?

A)P(Both black) = start fraction 121 over 361 end fraction
B)P(Both black) = start fraction 231 over 722 end fraction
C)P(Both black) = start fraction 231 over 703 end fraction
D) P(Both black) = start fraction 11 over 19 end fraction

Answer 1

Prob(Black on first draw) = 22/38
Prob(Black on 2nd draw) = 21/37
As these 2 events are independent we multiply the probabilities:-

Answer = 22*21 / 37*38 = 462/1406 = 231/703

Its C