Knewton Geometry

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Knewton Geometry

by akhilsuhag » Sun Aug 07, 2011 3:09 am
Image

Although they do have an explanation. It is a little complicated and goes over my head.

In rectangle WXYZ above, what is the perimeter of rectangle CXYD?

1. The area of CXYD is 32.
2. The perimeter of CXYD is one-half the perimeter of WXYZ.


[spoiler]OA: E[/spoiler]
Source: — Data Sufficiency |

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by Frankenstein » Sun Aug 07, 2011 3:20 am
Hi,
From(1):
Area is a*b where a and b are length and breadth
So, a*b=32
if a=8,b=4, 2(a+b) = 24
if a=16,b=2, 2(a+b) = 36
There are many more values possible
Not sufficient
From(2):
Can't find value from this data
Not sufficient

Both(1) and (2):
Still, unique value cannot be found.

Hence, E
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by Anurag@Gurome » Sun Aug 07, 2011 3:27 am
akhilsuhag wrote:In rectangle WXYZ above, what is the perimeter of rectangle CXYD?

1. The area of CXYD is 32.
2. The perimeter of CXYD is one-half the perimeter of WXYZ.
Say, WZ = CD = XY = a, WC = ZD = b, and CX = DY = c
Hence, we have to find 2(a + c)

Statement 1: ac = 32 ----> Not sufficient

Statement 2: 2(a + c) = 2(a + b + c)/2
Hence, (a + c) = b

Not sufficient

1 & 2 Together: ac = 32 and (a + c) = b
According to the value of b, a and c will have different values.

Not sufficient

The correct answer is E.
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