If the diameter of a circle is decreased by 50% then find the decrease in the area of circle

A. 75%

B. 50%

C. 25%

D. 20%

Answer: Option B

Solution(By Examveda Team)

Let Diameter = $R.
Radius = 2R.
Area = pi * radius² = pi * 4R
If diameter decrease 50%, then
D = 2R.
Now Radius = R.
Area = pi * R.
Decreased area = 4R *Pi - R * pi = 3R * Pi
% decreased Area = {(3R *pi)*100}/(4r *pi) = 75%.