Question

9. The top of a building which is in the shape of a hemisphere is to be painted. The circumference
of the base of the hemispherical portion is 88 m. If the cost of painting is Rs. 15 per square metre,
then what is the total cost of painting the top of the building?
*​

Answer 1

EXPLANATION.

• GIVEN

The circumference of the base of the

hemisphere portion = 88 m .

if the cost of painting is ₹ 15 per square meter.

To find the total cost of painting the top

of the building.

According to the question,

Let the radius = r

circumference of hemisphere = circumference of

circle with radius r .

=> 88 = 2πr

=> 88 = 2 X 22/7 X r

=> r = 14 cm .

Let the curved surface area of hemisphere

=> 2πr^2

=> 2 X 22/7 X 14 X 14

=> 1232 cm^2

Now,

cost of painting 1 cm^2 = ₹ 15

cost of painting 1232 cm^2 =

=> 1232 X 15 = ₹ 18480

Therefore,

Total cost of painting the top of

Building = ₹ 18480