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PS question - help please

by dqure040 » Thu Oct 22, 2015 1:11 pm
Company P had 15% more employees in December than it had in Jan. If company P had 460 employees in December, how many employees did it have in Jan? A 391, B 400, c 410, D 423, E 423

Solution: D = 1.15J, J= D/1.15, 460/1.15=400

BUT MY QUESTION IS WHY IS THE FOLLOWING WRONG?

J=0.85D, => 0.85*(460) = 391

What am I not understanding
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by Brent@GMATPrepNow » Thu Oct 22, 2015 1:27 pm
If the December number is 15% greater than the January number, we cannot also conclude that the January number is 15% less than the December number.

To illustrate this, let's look at a different example.
A = 100
B = 150
Notice that B is 50% greater than A. HOWEVER, A is not 50% less than B. In fact, A is 33 1/3% less than B.


To answer your question, let's let J = # of employees in January.

Company P had 15% more employees in December than in January
In other words, the December number is 15% greater than the January number
So, 460 = 1.15J
Solve to get: J = 460/1.15

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by GMATGuruNY » Thu Oct 22, 2015 1:35 pm
Company P had 15 percent more employees in December than it had in January. If Company P had 460 employees in December, how many employees did it have in January?

391
400
410
423
445
ALWAYS LOOK AT THE ANSWER CHOICES.
Here, the answer choices represent the number of employees in January.
Since there were 15% more employees in December, 15% of the correct answer choice must yield an integer value.
Only answer choice B is viable.

The correct answer is B.
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by dqure040 » Thu Oct 22, 2015 1:56 pm
Thanks Brent!
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