Question

The Volume of a sphare is 28/3 times the surface area calculate The surface area and the Volume of the sphere, correct to the nearest whole number.​

Answer 1

Given:

Volume of a sphere is $\dfrac{28}{3}$ times the surface area.

To find:

The surface area and the volume of the sphere.

Solution:

Volume of a sphere:

$V=\dfrac{4}{3}\pi r^3$              ...(i)

Surface area of a sphere:

$A=4\pi r^2$                      ...(ii)

Where, r is the radius of the sphere.

Volume of a sphere is $\dfrac{28}{3}$ times the surface area.

$V=\dfrac{28}{3}\times A$

$\dfrac{4}{3}\pi r^3=\dfrac{28}{3}\times 4\pi r^2$

Multiply both sides by 3.

$4\pi r^3=112\pi r^2$

$\dfrac{\pi r^3}{\pi r^2}=\dfrac{112}{4}$

$r=28$

Using (i), the volume of the sphere is:

$V=\dfrac{4}{3}\times \dfrac{22}{7}\times (28)^3$

$V\approx 91989$

Using (ii), the surface area of the sphere is:

$A=4\times \dfrac{22}{7}\times (28)^2$

$A=9856$

Therefore, the surface area of the sphere is 9856 sq. units and the volume of the sphere is 91989 cubic units.