Question

if the total surface of sphere is 154 cm2 find it's volume

Answer 1

TSA of sphere = 4*pi*r^2
                 154 = 4*22/7*r^2
                     r = 7/2 cm
vol. of sphere = 4/3*pi*r^3
                       = 4/3*22/7*7/2*7/2*7/2
                       = 539/3
                       = 179.6  cm^3    

Answer 2

T.S.A of sphere = 154 cm2
4πr2 = 154 cm2
4×22/7×r×r = 154
r×r = 154×7/22×1/4
r2 = 49/4
r = √49/4
r= 7/2 cm

Volume of sphere = 4/3 πr×r×r×r
= 4/3 ×22/7 × 7/2 ×7/2× 7/2 cm3
=77×7/3 cm3
= 539/3 cm3
= 179.66 cm3