If both the radius and height of a right circular cone are

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If both the radius and height of a right circular cone are increased by 20%, its volume will be increased by

1. 20%
2. 40%
3. 60%
4. 72.8%

Correct Option: D

Let height and radius both of a cylinder change by x%, then volume changes by

3x +

3x²

+

x³

% =

3 × 20 +

3 × 20 × 20

+

20 × 20 × 20

%

100

100²

100

10000

= (60 + 12 + 0.8)% = 72.8%