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Confusing DS ques.

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Confusing DS ques.

by myselfhari » Thu Jun 07, 2012 9:30 pm
I really feel ashamed of asking this small question. But, nevertheless, help me.

The surface area of a square tabletop was changed so that one of the dimensions was reduced by 1 inch and the other dimension was increased by 2 inches. What was the surface area before these changes were made?

(1) After the changes were made, the surface area was 70 square inches.
(2) There was a 25 percent increase in one of the dimensions.

OA : C <font color of ans is white>
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Source: — Data Sufficiency |

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by Anurag@Gurome » Thu Jun 07, 2012 10:11 pm
myselfhari wrote:The surface area of a square tabletop was changed so that one of the dimensions was reduced by 1 inch and the other dimension was increased by 2 inches. What was the surface area before these changes were made?

(1) After the changes were made, the surface area was 70 square inches.
(2) There was a 25 percent increase in one of the dimensions.
Say, the length of each side of the square = x inches
We need to find the area of the square = x² sq. inches

After the change, the length of the sides of the rectangle are (x - 1) and (x + 2) inches.

Statement 1:
--> (x - 1)(x + 2) = 70
--> (x² + x - 72) = 0
--> (x - 8)(x + 9) = 0
--> x = 8 or x = -9

As length of a side of a square cannot be negative, x must be equal to 8.

Sufficient

Statement 2: We know only one dimension has been increased.
So, (x + 2) = (x + 25% of x) = (x + x/4) = 5x/4
--> (5/4 - 1)*x =2
--> x/4 = 2
--> x = 8

Sufficient

The correct answer is D.
Anurag Mairal, Ph.D., MBA
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by myselfhari » Thu Jun 07, 2012 10:37 pm
Anurag Sir,

This is what i also got. Now i have a doubt, when the question is talking about square table top, is it definitely sure that the question is talking about a 2D picture. If it is a 3D picture the ques refers to (just in case, if it makes sense), then will the answer change from D to E ??
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