Question

There are 25 marbles in a bag. Some of the marbles are red and all the rest are blue. Bob picked up two marbles at random without replacement. The probability that he picks two blue marbles is 3/20

How many blue marbles are in the bag?

Answer 1

There are 15 blue marbles in the bag

Explanation:

3/20 divided by 2 = 3/40

Next make 40 to 25 as there are 25 marbles, to do that find the LCM of 25 and 40 which is 200

?/200 = 15/200

Hence there are 15 blue marbles in the bag