A right circular cone of circular base radius R and H resting on a plane. The cone is cut by a plane parallel to the base. The new circular cone-formed has a 12.5% volume of the older cone. What is the height of the new cone?

A right circular cone of circular base radius R and H resting on a plane. The cone is cut by a plane parallel to the base. The new circular cone-formed has a 12.5% volume of the older cone. What is the height of the new cone? Correct Answer h = H/2

Calculation:

Let r and h be the radius and height of the new cone.

Volume of new cone = (1/3) × π ×  r2 × h

⇒ 12.5% of the volume of the old cone

⇒ (1/8) × (1/3) × π × R2 × H      ---(1)

Also, since the new cone created from the old cone.

⇒ r/h = R/H

⇒ r = Rh/H

∴ Volume of new cone = (1/3) × π × (Rh/H)2 × h

⇒ (1/3) × π × (R2/H2) × h3      ---(2)

Using (1) and (2)

⇒ H3/8 = h3

⇒ h = H/2

Additional Information

The surface area of a circular cone = πr(l + r)   where l is the slant height and r is the radius of the circular base.

Bissoy MCQ

Related Questions

What will be the volume of the shape formed by carving out a right circular cone from a hemisphere of radius R cm, such that the volume of the cone is maximum and the base of the hemisphere is the base of the cone. I. Volume of the cone is 9π cm3.  II. Ratio of the total surface area of the cone to the hemisphere is (√2 + 1) : 3.