Question

a jar contains 36 marbles. it has 20 red, 12 black, and 4 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 red?

Answer 1

P(red) first drawn:
20/36=5/9
P(red) second drawn:
19/35

95/315 or 19/63. As a result, the probability that both marbles are red is 19/63. Hope it help!