Question

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

Answer 1

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

= \(\frac{4312}{3}\).