Question

A bag contains 20 marbles: 12 red, 4 blue, 3 yellow, and 1 green. Arielle takes out 2 marbles. What is the probability that they are both blue?

Answer 1

Total number of marbles in the bag =20

Number of blue marbles =4

Now we just want two blue marbles out of four.

Probability of taking out first marble which is blue =4/20

Now after we took out one blue marble , number of blue marbles left are 3.

Probability of taking out second marble which is blue =3/20

Total probability = 4/20 *3/20 = 12/400

So probability of taking out two blue marbles is 0.03 or 12/400.