If the radius of the base of a right circular cylinder is increased by 20% and the height is decreased by 30%, then what is the percentage increase/decrease in the volume?
Show answer & explanation
Correct answer: C
Explanation
The correct answer is option 3 i.e. Increase 0.8%
Concept
Volume of cylinder = π x r2x h
Application
Let the initial radius of cylinder = 5 units
New radius = 6 units
Let the initial height of cylinder = 10 units
New height = 7 units
Volume of initial cylinder = π x r2x h = π x 52x 10 = 250 π
Volume of new cylinder = π x r2x h = π x 62x 7 = 252 π
Percentage increase in volume = 100 x ( 252 π - 250 π) / (250 π) = 0.8%