If the radius of right circular cylinder is decreased by 10%, and the height s increased by 20%, then the percentage increase/decreasein its volume is:
Show answer & explanation
Correct answer: D
Explanation
The correct answer is option 4 i.e decrease quadrilateral by 2.8%
Explanation:
Volume of right circular cylinder = π r2h
Radius of a right circular cylinder is decreased by 10%, and the height is increased by 20%
So,
r1 = r × 90/100 = 0.9r
h1 = h × 120/100 = 1.2h
Volume of new right circular cylinder =π r2h1 = π (0.9r)2(1.2h) = 0.972(π r2h)
Decrements in volume = π r2h - 0.972(π r2h) = 0.028(π r2h)
Percentage Decrements in volume = (0.028(π r2h))/((π r2h)) × 100 = 2.8%