GMAT Prep - Ratio

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Source: — Problem Solving |

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by antyagi » Sat Jun 21, 2008 6:18 pm
If written in the eqn it is
4 + 6x = 4 + 4x + 1/5(4+4x)

Rsolving the above eqn you get x = 2/3
Thanks,
Ankur Tyagi

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by atlantic » Sun Jun 22, 2008 9:59 am
Rosh,

For sure the best way is algebrically, but if you are not an expert in algebra, you can also test the solutions.

The problem says.....

1st - 4'+x
2nd - 4'+2x
3rd - 4'+3x
4th - 4'+4x
5th - 4'+5x
6th - 4'+6x

Where x is the annual highness increase.

Starting to test E (as rule you should start by testing E and not A, going from E to A)

We get,

4th - 4+4*6/5=44/5
5th - 4+6*6/5=56/5, 5th-4th=12/5 which is greater than 1/5*44/5=44/25

So it's not E

Testing D

4th - 4+4*2/3=20/3
5th - 4+6*2/3=24/3, 5th-4th=4/3, and 1/5*20/3=4/3

OA is D.

Hope it helps