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Geometry - Squares

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Geometry - Squares

by shankar.ashwin » Mon Nov 07, 2011 11:13 am
The diagonal length of a square is 14.1 sq. units. What is the area of the square, rounded to the nearest integer?
(Sqrt(2) is approximately 1.41)


A) 96
B) 97
C) 98
D) 99
E) 100

OA - D
Last edited by shankar.ashwin on Mon Nov 07, 2011 12:05 pm, edited 1 time in total.
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by rijul007 » Mon Nov 07, 2011 11:19 am
diagonal = 10*root(2)
each side = 10*root(2)/root(2) = 10
Area = 100

Option E
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by vaibhavgupta » Mon Nov 07, 2011 11:29 am
shankar.ashwin wrote:The diagonal length of a square is 14.1 sq. units. What is the area of the square, rounded to the nearest integer?
(Sqrt(2) is approximately 1.41)


A) 96
B) 97
C) 98
D) 99
E) 100
Through Diagonal we find the side of the side and then the area ! :)

IMO E
If OA is A, IMO B
If OA is B, IMO C
If OA is C, IMO D
If OA is D, IMO E
If OA is E, IMO A

FML!! :/
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by neelgandham » Mon Nov 07, 2011 11:45 am
shankar.ashwin wrote:The diagonal length of a square is 14.1 sq. units. What is the area of the square, rounded to the nearest integer?
(Sqrt(2) is approximately 1.41)


A) 96
B) 97
C) 98
D) 99
E) 100
Length of the diagonal of a square is equal to (Square root(2))*Length of the side
Area of the square is equal to side*side = [(Length of the diagonal)/(Square root(2))]*[(Length of the diagonal)/(Square root(2))]
Implies, Area of the square is equal to [(Length of the diagonal)^2]/2 = 14.1 * 14.1 /2 = 99.405

IMO D

When the options are as close as provided above, I think we got to be really careful !
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by ripulgupta » Mon Nov 07, 2011 12:40 pm
Isn't question requiring so much calculation outside the scope of GMAT?

Thanks and regards,
Ripul
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by ariz » Tue Nov 08, 2011 12:25 pm
neelgandham wrote: Length of the diagonal of a square is equal to (Square root(2))*Length of the side
Area of the square is equal to side*side = [(Length of the diagonal)/(Square root(2))]*[(Length of the diagonal)/(Square root(2))]
Implies, Area of the square is equal to [(Length of the diagonal)^2]/2 = 14.1 * 14.1 /2 = 99.405
I did not know this, this is very useful. Thank you!
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by neelgandham » Tue Nov 08, 2011 3:31 pm
My Pleasure Ariz !

Shankar: Can you please post the OA and the source please ?
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by shankar.ashwin » Tue Nov 08, 2011 9:58 pm
The OA is D as mentioned. Question is from Nova's Math Bible.

Find attached the original explanation if interested.
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Screen Shot 2011-11-09 at 11.27.14 AM.png
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by kanumurisri » Wed Nov 16, 2011 6:48 am
neelgandham wrote:
shankar.ashwin wrote:The diagonal length of a square is 14.1 sq. units. What is the area of the square, rounded to the nearest integer?
(Sqrt(2) is approximately 1.41)


A) 96
B) 97
C) 98
D) 99
E) 100
Length of the diagonal of a square is equal to (Square root(2))*Length of the side
Area of the square is equal to side*side = [(Length of the diagonal)/(Square root(2))]*[(Length of the diagonal)/(Square root(2))]
Implies, Area of the square is equal to [(Length of the diagonal)^2]/2 = 14.1 * 14.1 /2 = 99.405

IMO D

When the options are as close as provided above, I think we got to be really careful !

If it was not mentioned in the question, about the assumption, then what ever you said is correct.
But with the assumption mentioned, I doubt what the answer is....

-Srini
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by neelgandham » Wed Nov 16, 2011 7:34 am
kanumurisri wrote: If it was not mentioned in the question, about the assumption, then what ever you said is correct.
But with the assumption mentioned, I doubt what the answer is....
-Srini
The Official answer is D as mentioned. The question is from Nova's Math Bible.
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by MBA.Aspirant » Wed Nov 16, 2011 4:11 pm
area = 1/2 Diagonal ^2

(14.1 * 14.1)/2 = 99 to the nearest integer
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