A solid cylinder is reduced in radius by 20% and increased in height by 50%. What net percentage change occurs in its volume?
Show answer & explanation
Correct answer: D
Explanation
Radius decreased by 20%, height increased by 50%
Volume = r²h
New radius = 0.8r ⇒ r² = (0.8)² = 0.64
New height = 1.5h
New volume = 0.64 × 1.5 = 0.96
Change = 0.96 − 1 = −0.04 = 4% decrease