Question

A jar contains 30 marbles. It has 10 red, 8 black and 12 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 green?

P(Both Green) =
4 / 5


P(Both Green) =
11 / 75


P(Both Green) =
28 / 325


P(Both Green) =
22 / 145

Answer 1

P(Both Green) = 22/145

Explanation:

The probability of drawing green on the first drawn is P(First Green) = 12/30 = 2/5.

Having drawn green in the first drawn, the probability of drawning green in the second drawn is P(Second Green) = 11/29.

Then, the probability that both marbles are green is obtained by multiplying both probabilities as follows:
`P(Both Green) = (2*11)/(5*29) = 22/145`