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What is the % change in the area of a rectangle ........

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by pzazz12 » Wed Oct 06, 2010 4:30 am
What is the % change in the area of a rectangle when its length increases by 10% and its width decreases by 10%?

A. 0%
B. 20% increase
C. 20% decrease
D. 1% decrease
E. Insufficient data
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by neerajkumar1_1 » Wed Oct 06, 2010 4:42 am
u can solve it by algebra...
but i suppose putting values will make it even more easy..

Let original L and B = 10

Area A = LB = 100
New Length L`= 1.1 * 10 = 11
New Breadth B` = .9 * 10 = 9

New Area A` = L` * B` = 99

Diff = A` - A = -1
the -ve sign signifies decrease
since there is a decrease
and the original value is 100

there is a 1 % dec

IMO D
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by Yanat » Wed Oct 06, 2010 7:06 am
IMO it is 1% decrease.
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by pzazz12 » Wed Oct 06, 2010 11:34 pm
neerajkumar1_1 wrote:u can solve it by algebra...
but i suppose putting values will make it even more easy..

Let original L and B = 10

Area A = LB = 100
New Length L`= 1.1 * 10 = 11
New Breadth B` = .9 * 10 = 9

New Area A` = L` * B` = 99

Diff = A` - A = -1
the -ve sign signifies decrease
since there is a decrease
and the original value is 100

there is a 1 % dec

IMO D
thank you....but can you explain me in simple method.........
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by pkan51 » Thu Oct 07, 2010 1:30 am
question like this I just test it with simple number.

I used 5x5=25 and matched it with 5(1.1)x5(.9)=(5.5)x(4.5)=24.75

(25-24.75)/24.75 is around 1%. I assumed the answer is D
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