If written in the eqn it is
4 + 6x = 4 + 4x + 1/5(4+4x)
Rsolving the above eqn you get x = 2/3
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GMAT Prep - Ratio
Source: Beat The GMAT — Problem Solving |
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
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
