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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) ===> 36
Diminished in area = 100 - 36 = 64%

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Comments ( 5 )

  1. Kumar Nigam
    Kumar Nigam :
    3 years ago

    40%=2/5
    L=5-3
    B=5-3
    L*b=25-9
    Diffrence=16
    16/25*100=64%

  2. Maa Friends28
    Maa Friends28 :
    4 years ago

    =>> -a-b+(ab/100) = 64% ( a=40; b=40)...

  3. Gagan Ramgharia
    Gagan Ramgharia :
    5 years ago

    100-40=60
    60×40%=24
    24+40=64

  4. Examveda
    Examveda :
    6 years ago

    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.

  5. Abbhinav Abbhi
    Abbhinav Abbhi :
    6 years ago

    i did not understand the mind calculation can you please explain me

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