If radius of a cylinder is increased by 20% keeping the height unchanged, then by what percent does the volume of the cylinder increase?
Show answer & explanation
Correct answer: D
Explanation
The correct answer is option 4 i.e. 44%.
Formula used:
Volume of cylinder = πr2h ----- (1)
Calculations:
According to the question;
Let the radius of the cylinder be 5x
If increased by 20% = 120% of 5x = 6x
Height remain unchanged
Volume of cylinder (r = 5x) = π(5x)2h
Volume of cylinder (r = 6x) = π(6x)2h
Required increase in area = πh(36x2 - 25x2)/(πh25x2) × 100
⇒ [11x2/25x2] × 100 = 44%