For making a toy, a hemisphere is attached at one end of a cylinder and a cone is attached at the other end of the cylinder. The cylinder, the cone, and the hemisphere have a common radius of 4.2 cm. The height of the cylinder and that of the cone is 7 cm. Find the volume (in cm3) of the toy. (Use π = 22/7)
Show answer & explanation
Correct answer: C
Explanation
The correct answer is option 3 i.e. 672.672.
Given,
The radius of the cylinder, cone, and hemisphere = 4.2 cm
Height of cylinder and cone = 7 cm
We know,
Volume of cylinder = πr2h
The volume of cone = (1/3)πr2h
Volume of hemisphere = 2/3πr3
Volume of the toy = Volume of Cylinder + Volume of cone + Volume of Hemisphere
⇒ πr2h + (1/3)πr2h + 2/3πr3
⇒ πr2(h + 1/3h + 2/3r)
⇒ 22/7 × 4.22 × (7 + 7/3 + 2.8)
⇒ 55.44 × (7 + 21 + 8.4)/3
⇒ 18.48 × 36.4
⇒ 672.672