Saturday, July 09, 2011

another Math Beast challenge

From the Manhattan GRE website's Math Beast Weekly Challenge page:

x and y are positive integers such that x > y.

Quantity A: xy
Quantity B: yx

(a) Quantity A is greater.
(b) Quantity B is greater.
(c) The two quantities are equal.
(d) The relationship cannot be determined from the information given.

This one's pretty damn easy. If you don't get it, even I will be ashamed of you. Highlight the bracketed response below to see the correct answer.

The correct response is [in my pants... and you know the only reason you highlighted this text was that you were too fucking lazy to figure out the goddamn answer for yourself].



Kevin Kim said...

Fine, fine-- the answer is D: the relationship cannot be determined. See what happens when x is 2 and y is 1, then see what happens when x is 3 and y is 2. In the first case, Column A would be 2 (from 1 x 2) and Column B would be 1 (from 1^2). In the second case, Column A would be 6 (from 2 x 3) and Column B would be 8 (from 2^3). In one case, Column A is greater; in the other, Column B is greater. Without knowing what values the variables actually are, it's impossible to know which column, A or B, is greater.

Anonymous said...

No I highlighted it to make sure you had the right answer. I always try the simplest values in a problem like this before doing much analysis. It often provides a quick path to the answer. I did x=2, y=1 and x=3 and y=2 and get a reversal.

Kevin Kim said...

Yes, the "plug-in" method is still a valid and useful test-taking strategy. Sorry if the "hidden" answer seemed insulting; that was an example of my ever-leprous sense of humor.