Question

If the radius of a right circular cone is increases by 50%, then its volume increases by

• A.
  75%
• B.
  100%
• C.
  125%
• D.
  237.5%

Answer 1

The correct option is C

125%
$V=\frac{1}{3}\pi (R{)}^{2}H$

$V^{\prime }=\frac{1}{3}\pi (1.5R{)}^{2}H$

$=\frac{1}{3}\pi 2.25R^{2}H=2.25V$

$\therefore$ its volume increases by 125% as

$\left[\frac{2.25V-V}{V}\right]\times 100=125$