Question

There are 10 marbles in a bag .2 red, 5 green and 3 blue. Aron picks up 2 marbles without

replacing the first marble. What is the probability that both the marbles are blue.

Answer 1

It would be 0.09

Explanation:

First, note the original Probability for picking a blue marble in the first try:

0.3

Now, if this were to happen again, knowing that no marbles would be taken out, it would be another chance of 0.3 for Aron to pick up a blue marble on his second pick up.

Due to these being independent events, you can do:

0.3*0.3 = 0.09

To get your answer, 0.09.

Answer 2

27/90 = 3/10

Explanation:

Calculate the probability that neither is blue

7/10 * 6 / 9

63/90

Now the remainder of the choices are what the probability is when both are blue

1 - 63 / 90

27/90 is the probability of choosing 2 blues.