The radius of the base of a right circular cone is increased by 15% keeping the height fixed. The volume of the cone will be increased by

- 34.75%
- 32.25%
- 31%
- 30%

**Answer**

Volume of a cone = πr^{2}h, where r is the radius of base and h is the height of the cone.

So, let initial volume be = V_{1}

Final volume, V_{2} = πR^{2}h, where R = r(1 + 0.15) = 1.15r

So, V_{2} = 1.3225 πr_{2}h

Increase in volume = (V_{2} - V_{1}) /V_{1} × 100%

= (1.3225 πr^{2}h - πr^{2}h)/πr^{2}h × 100% = 32.25%

**The correct option is B.**