# Cost of whitewashing a sphere is 1232₹ at the rate of 2₹/cm^2.

Cost of whitewashing a sphere is 1232₹ at the rate of 2₹/cm^2. What is the volume of a sphere? (Take π = $$\frac{22}{7}$$)

A. $$\frac{4324}{3}$$

B. $$\frac{4317}{5}$$

C. $$\frac{4312}{3}$$

D. $$\frac{4312}{7}$$

This question was addressed to me in an interview for job.

I would like to ask this question from Volume of a Sphere topic in division Surface Areas and Volumes of Mathematics – Class 9

Right answer is C. $$\frac{4312}{3}$$

The explanation is: Area of a sphere = $$\frac{Total \,cost \,of \,whitewashing}{Rate \,of \,whitewashing/cm^2}$$

= $$\frac{1232}{2}$$

= 616 cm^2

We know that total surface area of a sphere = 4πr^2

4πr^2 = 616

r^2 = $$\frac{616*7}{22*4}$$

= 49

Therefore, r = 7cm

Now, volume of a sphere = $$\frac{4}{3} πr^3$$

= $$\frac{4}{3} * \frac{22}{7}$$ * 7^3

= $$\frac{4312}{3}$$.