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Bunuel
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Hi All,

This question is essentially a 'lift' of an OG question.

In the GMAT2016: PS Question 194 (page 180).
In the GMAT2015/OG13: PS Question 181 (page 177).

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CounterSniper

(x/a)*100 =b

let a = 100 and x = 10 then b =10
in this case
a is = 100/x times b

now ,

let a=150 and x =50 then b = 75
in this case
a is =100/x times b

for confirmation

let a =200 and x =30 then b = 120
in this case
a is again = 100/x times b

so E 100/x


Hi CounterSniper,

I think you mean in highlighted part that (x*a)/100 =b such that in you example (30*200)/100= 120
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davedekoos
Given: x percent of a = b

\(a*(\frac{x}{100})=b\)

What we're being asked: a = b*(something in terms of x)

Rearrange our original equation

\(a=b*(\frac{100}{x})\)

Answer: E

We can check by testing values. When testing values, it's important to avoid values that might give false positives. You want numbers that are easy to work with, but will give you unique answers.
let a = 90 and x = 20, then b = 18

\(b*(\frac{100}{x}) = 18*(\frac{100}{20}) = 90\)

Checks out.

If instead I had chosen a = 100 and x = 10, then b = 10. Then b*10 = a, and both answers C and E could work. It's not always easy, but one should always try to choose numbers that will give different results for each answer choice.

Those are almost the answer I chose and apparently why I got it wrong! x=10, a=200, b=20. C and E work for both.
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Hi All,

Since some of posts have mentioned coming across more than one answer that 'matches' what you're looking for, we should take a moment to talk about how to AVOID choosing VALUES that will lead to those duplicate solutions.

Consider the 5 answer choices to this prompt:

A. 100x
B. 10x
C. x
D. 10/x
E. 100/x

What values of X will lead to a pair of 'matching' answers (hint: think about the numbers that appear in the 5 answer choices)?

IF....
X = 1, then Answer A and E will be the SAME
X = 10, then Answer C and E will be the SAME

Therefore, you should AVOID using these numbers when you TEST VALUES.

GMAT assassins aren't born, they're made,
Rich
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Hello from the GMAT Club BumpBot!

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