2014-07-30 09:00:24

A t-shirt is to be chosen at random from a drawer full of t-shirts. The probability that the t-shirt chosen will be white is 2/7. Which of the following could NOT be the number of t-shirts in the drawer?

(A) 21
(B) 35
(C) 37
(D) 42
(E) 49

The correct answer is C
Explanation: Probability is the number of desired outcomes divided by the number of total outcomes. Thus, if the total outcomes here is 7, then the total number of t-shirts must be a multiple of 7, since it would be impossible to pick a fraction of a t-shirt. All of the answer choices are divisible by 7 except for 37. There cannot be a 2/7 chance of choosing a white t-shirt from a drawer with 37 total t-shirts. Choice C is correct.