A cone is 8.4 cm high and the radius of its base is 2.1 cm. It is melted and recast into a sphere. The radius of the sphere is
A) 4.2 cm
B) 2.1 cm
C) 2.4 cm
D) 1.6 cm
The correct option is (B): 2.1 cm
Given, the height of the cone =8.4 cm
Radius of the base =2.1 cm
Volume of a cone =13πr2h=13×π×(2.1)2×8.4
The cone is melted and recast into a sphere.
Let the radius of a sphere be R.
Then, volume of the sphere = volume of the cone
Hence, the radius of the sphere is 2.1 cm.