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Source: — Data Sufficiency |

by Anurag@Gurome » Thu Sep 06, 2012 11:29 pm
grandh01 wrote:What is the area of the rectangular field?

1) The diagonal is twice the width.
2) Length = 173 feet

OA IS C
Image

Area of rectangle = length * width = L * W sq units

(1) Diagonal = 2W
So, by Pythagoras Theorem, (2W)² = L² + W² or 4W² = L² + W² or 3W² = L² but we do not know the value of L or W; NOT sufficient.

(2) Length = 173 feet
Area = 173 * W, but again we do not know the value of W; NOT sufficient.

Combining (1) and (2), since we know L = 173 ft, so we can find W using the equation, 3W² = L².
Hence, we can find the area of rectangular field; SUFFICIENT.

The correct answer is C.
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by GMATGuruNY » Fri Sep 07, 2012 3:42 am
grandh01 wrote:What is the area of the rectangular field?

1) The diagonal is twice the width.
2) Length = 173 feet

OA IS C
The diagonal of a rectangle splits the rectangle into two congruent right triangles.
The diagonal of the rectangle = the hypotenuse each right triangle.

Statement 1: The diagonal is twice the width
ALWAYS LOOK FOR SPECIAL TRIANGLES.
In a 30-60-90 triangle, the sides are in the following ratio:
x : x√3 : 2x.
Note the values in red.
If the hypotenuse of a right triangle is twice one of the legs, the triangle is a 30-60-90 triangle.
Since the diagonal here is twice the width of the rectangle, the diagonal splits the rectangle into two 30-60-90 triangles.
No way to determine any exact lengths.
INSUFFICIENT.

Statement 2: Length = 173 feet
No way to determine the width.
INSUFFICIENT.

Statement 1 and 2 combined:
The length of the rectangle = 173 = the length of the longer leg of each 30-60-90 triangle.
Since x√3 = 173, x = 173/√3.
Thus, the area of the rectangle can be determined.
SUFFICIENT.

The correct answer is C.
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