A marble shop contains 6 blue marbles, 6 red marbles, and 6 green marbles. If 4 marbles are purchased at random from the shop, what is the probability that the 4 marbles will be the same color?
Options:
(A) 1/68
(B) 60/68
(C) 13/68
(D) 13/48
(E) 1/48 Stream of consciousness first, then make a decision:
It doesn't matter which type of card you choose, so:
Probability of choosing 1st card: 1
Probability of choosing 2nd card of the same type: 5/17
Probability of choosing 3rd card of the same type: 4/16
Probability of choosing 4th marble of the same type: 3/15
Multiply and you get 1/68
Thus, the answer is (A).