There is a hemisphere hollow from inside in which there is a cone inscribed whose base is the diameter of the hemisphere. If the radius of the hemisphere is 6 cm, then find the ratio of the volume of hemisphere and volume of the remaining part of hemisphere when cone is dug out from it.

There is a hemisphere hollow from inside in which there is a cone inscribed whose base is the diameter of the hemisphere. If the radius of the hemisphere is 6 cm, then find the ratio of the volume of hemisphere and volume of the remaining part of hemisphere when cone is dug out from it. Correct Answer 2 : 1

Given:

Radius of the hemisphere = 6 cm

Diameter of base of hemisphere = Diameter of base of cone

Formula used:

Volume of hemisphere = 2πr3/3

Volume of cone = πr2h/3

As cone is inscribed in the hemisphere so, the height of the cone will be equal to the radius of the hemisphere

Calculation:

Radius of the base of hemisphere = 6 cm

⇒ Volume of hemisphere = 2π × 6 × 6 × 6/3 cm3 = 144π cm3

Now,

Radius of cone = radius of hemisphere = 6 cm

Height of cone = 6 cm

⇒ Volume of cone = π × 6 × 6 × 6/3 cm3 = 72π cm3

Now, Volume of the remaining part = Volume of hemisphere – volume of cone

⇒ Volume of the remaining part = 144π cm3 – 72π cm3 = 72π cm3

∴ Ratio of Volume of hemisphere and Volume of remaining part = 144π : 72π

⇒ 2 : 1

Short Trick:

Radius of both hemisphere and cone is equal and the height of the cone will also be equal to the radius of the hemisphere

So, h = r = 6 cm

Volume of the remaining part = 2πr3/3 – πr3/3         (as r = h)

⇒ Volume of the remaining part = πr3/3

⇒ π6 × 6 × 6/3 = 72π cm3

∴ Ratio of Volume of hemisphere and Volume of remaining part = 144π : 72π

⇒ 2 : 1

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.