The following is a practice question from a GRE preparation book.
A case of $100$ candy bars is sold at a discount of $\$0.36$ per bar.
Quantity A: the discount per case
Quantity B: 36%
(a) A is greater
(b) B is greater
(C) The two quantities are equal
(d) The relationship cannot be determined from the information given
My approach: Quantity B is 36%, which is simply 0.36
Quantity A is 0.36 * 100 = 36
Therefore A > B.
However the answer I'm given is D. Where have I made a mistake?
The discount per case means the price after discount. However, the discount per case is the discounted amount divided by the total amount. Since only the discounted amount is known ($36), you cannot find the discount per case. Per case indicates that you know how much the case costs in the first place.