If the radius of a right circular cylinder is decreased by 40% and its height is increased by 75%, its volume will be decreased by:
Show answer & explanation
Correct answer: C
Explanation
The correct answer is option 3 i.e 37%.
New radius = 60% of r = 0.6r and New height = 175% of h = 1.75h
Volume = π × r² × h
New volume = π × (0.6r)² × 1.75h = π × 0.36r² × 1.75h = π × r² × h × 0.36 × 1.75 = π × r² × h × 0.63
The new volume is 63% of the original
So decrease = 100% - 63% = 37%