A conical tent is set to accommodate 15 persons. Each person must have 5 square metres of space on the ground and 30 cubic metres of air to breathe. What is the height of the cone?

Correct option is D

Since each person will require 5 $$m^2$$​of base area
total base area required will be =$$\pi \times r^2$$​ = 5× 15 = 75 $$m^2$$​​
Since each person will require 30 $$m^3$$​ of air
So, total Volume of air required will be = 15 × 30 = 450$$m^3$$​​
Let the height of the cone be h m.
$$\frac{1}{3}$$​ π × $$r^2$$​× h = 450
$$\frac{1}{3}$$​ × 75× h = 2000
 h = 18 m.