Bunuel
The enrollment at a local private school for the new school year is 10% more than the enrollment at this time last year. The number of female students increased by 5%, and the number of male students increased by 20%. Female students make up what fraction of the current enrollment at the private school?
(A) 1/5
(B) 4/11
(C) 1/2
(D) 7/11
(E) 4/5
We'll translate our question into equations so we understand what we need to do.
This is a Precise approach.
Say E is the original enrollment and m,f are the original numbers of males and females, respectively.
Then m + f= E and 1.2m + 1.05f = 1.1 E are our two equations.
We need to calculate 1.05f/1.1E so we'll use our two equations to cancel out m.
Multiplying the first equation by 1.2 gives 1.2m + 1.2f = 1.2E and subtracting the second equation from this gives
0.15f = 0.1E. Then E = 1.5f. So let's say f = 100, then E would equal 150.
1.05f = 105 and 1.1E = 165.
Then our ratio is 105/165 = 21/33 = 7/11.
(D) is our answer.