A dome of a building is in the form of a hemisphere. From inside, it was white-washed at the cost of Rs 498.96. If the cost of white-washing is Rs 2.00 per square metre, find the
(i) inside surface area of the dome, (ii) volume of the air inside the dome.
Solution:
Curved surface area of hemisphere = cost/rate
= 498.96/2 = 249.48 sq m
Or, 2 π r2 = 249.48
Or, r2 = (249.48 X 7)/(2 X 22)
Or, r = 6.3 m
Volume of hemisphere = 2/3 π r3
= (2/3) X (22/7) X (6.3)3 = 523.908 cubic m
