# Find the Radius of the Hemisphere

A hemisphere of iron is melted and recast in the shape of a right circular cylinder of diameter 18 cm and height 162 cm. The radius of the hemisphere is

- 27 cm
- 9 cm
- 6 cm
- 12 cm

**Answer: (1) 27 cm**

**Explanation:-
**Given-

Diameter of the cylinder = 18 cm

Then, the radius of the cylinder = 18/2 = 9 cm

Then height of the cylinder = 162 cm

**Formula-**

** The volume of the cylinder = Pai x r ^{2} h**

**The volume of the cylinder = Pai x (9)**

^{2}x 162The volume of the hemisphere = 2 Pai x r

^{3}/3

According to the question,

Pai x (9)^{2} x 162 = 2Pai x r^{3}/3

9 x 9 x 9 x 18 = 2 x r^{3}/3

9 x 9 x 9 x 9 x 3 = r^{3}

r^{3} = 9^{3} x 3^{3}

r = 9 x 3

r = 27

Then, the radius of the hemisphere is 27 cm

Hence, the answer is (1) 27 cm.