Question

If the surface area of sphere is 616 cm^2, then its radius is 

A) 3.5 cm 

B) 7 cm 

C) 14 cm 

D) 21 cm

Answer 1

Correct option is (B) 7 cm

Let radius of the sphere is r cm.

\(\therefore\) \(4\pi r^2=616\)   \((\because\) Surface area of sphere \(=4\pi r^2)\)

\(\Rightarrow\) \(r^2=\frac{616}{4\pi}=\frac{616\times7}{4\times22}\)

\(=\frac{28\times7}4=7\times7=7^2\)

\(\Rightarrow\) r = 7

Hence, radius of sphere is 7 cm.

Answer 2

Correct option is   B) 7 cm