Each side of a rectangular field diminished by 40%. By how much per cent is the area of the field diminished?
A. 32%
B. 64%
C. 25%
D. 16%
Answer: Option B
Solution(By Examveda Team)
Let the Original length of the rectangle be 20 unit and breadth be 10 unit. Then Original Area = length *breadth = 20*10 = 200 Square unit. 40% decrease in each side, then Length = (20 - 40% of 20) = 12 unit. Breadth = (10 - 40% of 10) = 6 unit. Now, Area = 12 × 6 = 72 Square unit. Decrease in area = 200 - 72 = 128 square unit. % Decrease in Area = $$\frac{{128}}{{200}} \times 100 = 64\% $$ Mind Calculation Method: Let the original area be 100 square unit. 100 === 40%↓(decrease in length) ==⇒ 60 === 40%↓ === (decrease in breadth) ===> 36Diminished in area = 100 - 36 = 64%
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Comments ( 6 )
Related Questions on Percentage
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Maa friends is correct method....
40%=2/5
L=5-3
B=5-3
L*b=25-9
Diffrence=16
16/25*100=64%
=>> -a-b+(ab/100) = 64% ( a=40; b=40)...
100-40=60
60×40%=24
24+40=64
I will Suggest you to go through the theory on Net Percentage Change. It will help you to understand the concept. Click Here for the Net Percentage Change theory.
i did not understand the mind calculation can you please explain me