A sphere and a cube have equal surface areas. The ratio of the volume of the sphere to that of the cube is:
Show answer & explanation
Correct answer: A
Explanation
The correct answer is Option 1 i.e. .
The surface area of cube = 6 a2
The surface area of sphere = 4π r2
Volume of a cube = a3
Volume of sphere = 4π r3/3
6a2 = 4 π r2
⇒ a2 = 4π r2/6
⇒ a2/r2 = 4π /6
⇒ a/r = 2 √π /√6
Assuming, a = 2√π , r = √6
Volume of a cube = (2 √π)3
⇒ 8π√π
Volume of sphere = 4 π × (√6)3/3
⇒ 4π × 6 √ 6/3 = 4 π × 2 √6
⇒ 8π √6
The ratio of the volume of sphere and cube = 8π √6 ÷ 8π √π
⇒ √6/√π