Question

Find the cost of painting a hemispherical dome of diameter 10 m at the rate of Rs 1.40 per square metre. 

Answer 1

Diameter of the hemispherical dome = 10 m 

Therefore, radius of dome = 5 m 

Curved surface area = `2pir^2`

 = `2 xx 22/7 xx 5 xx 5`

= 157.14 m²

Cost of painting one sq. metre = Rs. 1.40 

Cost of painting 157.14 m² = Rs.(1.40 x 157.14) 

= Rs. 219.99 = Rs 220

Therefore, cost of painting the dome = Rs 220