A bag contains 3 white marbles and 3 black marbles. If each of 3 girls and 3 boys randomly selects and keeps a marble, what is the probability that all of the girls select the same colored marble?  Choose the correct choice from the following choices:
A) 1 / 35
B) 1 / 10
C) 1 / 15
D) 1 / 20
E) 1 / 25

Rationale: first , total ways to select for all boys and girls , i . e 6 ! / ( 3 ! * 3 ! ) = 6 * 5 * 4 * 3 * 2 * 1 / 3 * 2 * 1 * 3 * 2 * 1 = 20 then there are one two way girls can have all same colors , either white or black . the number of ways in which 3 girls can select 3 white balls = 3 c 3 = 1 the number of ways in which 3 girls can select 3 black balls = 3 c 3 = 1 therefore , total favorable outcomes / total outcomes = 2 / 20 = 1 / 10 b
Answer: B