SOLUTION: 7 red 3 green and 10 black marbles in a bag. 2 marbles selected at random, what is the probability that both are green.

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Question 747693: 7 red 3 green and 10 black marbles in a bag.
2 marbles selected at random, what is the probability that both are green.
Answer by mikeebsc(26) About Me  (Show Source):
You can put this solution on YOUR website!
First, add the number of marbles together = 20.
Event A:1st marble is drawn is green: Probability is 3/20
Event B:2nd marble is drawn is green: Probability is 2/19
P(B) depends on the P(A)
P(A) = 3/20
P(B|A) = 2/19 (The probability of B happening assuming A happened)
P(A and B)= P(A) * P(B|A)
P(A and B) =3/20 * 2/19= .0016