One strategy you should always employ on PS:
scan the answer choices & think logically / try to estimate before diving into solving.
If 25% of n = 37.5% of m, (i.e. a smaller percentage of n = a larger percentage of m), then
n must be larger than m. (Assuming positive values. If n and m were negative, this would make n less than m, but with a larger absolute value. This is the same idea for our analysis here).
Therefore, n/m must be greater than 1, so
12n/m must be greater than 12. Or another way to estimate it: 12 times a larger number divided by the smaller number must be larger than 12.
Eliminate any answer choice less than 12:
A) 18 --> maybe
B) 32/3 --> this is a little less than 11 (33/3). Eliminate.
C) 8 --> eliminate
D) 3 --> eliminate
E) 9/8 --> barely greater than 1. Eliminate.
The only answer greater than 12 is A, so that must be the answer! We didn't have to calculate.
Estimation like this will of course not get you all the way to the right answer on every single problem, but it's a good practice to get into. It can save time on questions like this, and help to prevent mistakes on other problems.
More here:
https://www.manhattanprep.com/gmat/blog ... -pen-down/
And please edit your post to list your source!
Ceilidh Erickson
EdM in Mind, Brain, and Education
Harvard Graduate School of Education