Bunuel wrote:

A bag contains 5 white marbles and 5 black marbles. If each of 5 girls and 5 boys randomly selects and keeps a marble, what is the probability that all of the girls select the same colored marble?

A. 1/126

B. 1/120

C. 1/24

D. 4/25

E. 1/2

Kudos for a correct solution.

Consider a case when all girls select black marbles...So Girl 1 will chose 1 black marble out of 10..and black marble will be chosen from 5 Black marbles

Girl 1 will have a probability of picking black marble 5/10

Girl 2 will have to pick a black marble out of 4 and total remaining no. of marbles 9=4/9

So we have Probability of all girls selecting black marbles as 5/10*4/9*3/8*2/7*1/6 =1/252

Since Girls can also select white marbles so we will have 2 cases so Probability of girls selecting all same colour marbles is 2*1/252 or 1/126

Ans is A

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