This question presents the following situation: "Uncle Bruce is baking chocolate chip cookies. He has 36 ounces of dough (with no chocolate) and 15 ounces of chocolate. How many ounces of chocolate are left over if he uses all the dough but only wants the cookies to consist of 20% chocolate?"

(A) 3
(B) 6
(C) 7.2
(D) 7.8
(E) 9

The correct answer is (B). I am confused about the part where 20% chocolate is represented by the ratio of 4 (dough) : 1 (chocolate). I thought that 20% = 1/5, so the ratio should rather be 5 (dough) : 1 (chocolate). Could you please explain the issue in this ratio question?

For every 4 parts of dough there is 1 part chocolate. 4:1 is how you would express this ratio of doughto chocolate

Thus the percentage of chocolate is 1 part out of 5 total parts (1+4).

1 / 5 = 20%

Hope that helps.