gmatser1 wrote:
At the rate of f floors per m minutes, how many floors does an elevator travel in s seconds?
(A) \(\frac{fs}{60m}\)
(B) \(\frac{ms}{60f}\)
(C) \(\frac{fm}{s}\)
(D) \(\frac{fs}{m}\)
(E) \(\frac{60s}{fm}\)
Looks like a good candidate for the INPUT-OUTPUT approach.
Let's INPUT some values for f, m and s.
Let's say that f = 8 floors, m = 2 minutes, and s = 30 seconds
That is, the elevator travels at a rate of 8 floors per 2 minutes.
How many floors does an elevator travel in 30 seconds?
Well, 8 floors in 2 minutes translates to 4 floors in 1 minute, and
2 floors in 30 seconds.
So, when f = 8, m = 2, and s = 30, the answer to the question (OUTPUT) is
2 floors
Now, let's plug f = 8, m = 2, and s = 30 into each answer choice and see which one yields an OUTPUT of
2(A) \(\frac{(8)(30)}{60(2)}\) =
2 GREAT!
(B) \(\frac{(2)(30)}{60(8)}\) =
1/8 ELIMINATE
(C) \(\frac{(8)(2)}{(30)}\) =
8/15 ELIMINATE
(D) \(\frac{(8)(30)}{(2)}\) =
120 ELIMINATE
(E) \(\frac{60(30)}{(8)(2)}\) =
some big number ELIMINATE
Answer: A
For more information on this question type and this approach, we have some free videos:
- Variables in the Answer Choices -
http://www.gmatprepnow.com/module/gmat- ... /video/933 - Tips for the Algebraic Approach -
http://www.gmatprepnow.com/module/gmat- ... /video/934 - Tips for the Input-Output Approach -
http://www.gmatprepnow.com/module/gmat- ... /video/935 Cheers,
Brent
_________________
Test confidently with gmatprepnow.com