Bhai wrote:

15. Alan has a flock of sheep from which he will choose 4 to take with him to the livestock show in Houston. If Alan has 15 distinct possible groups of sheep he could take to the show then which of the following is the number of sheep in his flock?

(A) 30

(B) 15

(C) 7

(D) 6

(E) 5

My vote for D

4 sheeps from X 15 possblie ways So X=6 Because Only this way you can get 15 possible arrangments while choosing 4 sheeps!

Here is formula C4,X=15 lets substitute x with answer choices!In "which of the following"questions I start with the D or E

When X= 6 C4,6=6*5*4*3/1*2*3*4=15 Bingo