ratio

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ratio

by GmatKiss » Tue Aug 16, 2011 1:03 pm
If p1 and p2 are the populations and r1 and r2 are the numbers of representatives of District 1 and District 2, respectively, the ratio of the population to the number of representatives is greater for which of the two districts ?
(1) p1 > p2
(2) r2 > r1
Source: — Data Sufficiency |

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by sumgb » Tue Aug 16, 2011 2:59 pm
stmnt 1: insuff as you do not know the relation between r1 and r2
stmnt 2: insuff as you do not know the relation between p1 and p2
together, since
p1 > p2 and
r2 > r1 therefore
p1r2 > p2r1 (population and representation cant be negative and both inequalities face the same direction so multiply directly. I tested this using +ve numbers and it seems to work fine.)

which is nothing but, p1/r1 > p2/r2. sufficient. answer C. hope this helps.

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by gmatboost » Wed Aug 17, 2011 8:11 pm
From the beginning you should write it as:
p1/r1 ? p2/r2

Whenever you see proportions with positive numbers, it is a good idea to cross-multiply:
p1r2 ? p2r1

So that way you have your eye out for any statement that helps you answer either of the above equivalent statements
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