Question

A dome of a building is in the form of a hemisphere. From inside, it was white washed at the cost of Rs 554.40. If the cost of white washing is Rs 5 per square metre, find the
(i) inner surface area of the dome, (ii) volume of the air inside the dome.

Answer 1

Answer:

the inner surface area of the dome is nothing but the total cost of whitewashing divided by the rate per metre. hence inner surface area= 498.96 / 2 = 249.48 m^2. now, inner surface area = 2πr^2. therefore 2πr^2 = 249.48, which gives r = 6.3 m. so, volume = 2/3*πr^3 = 523.908 m^3.