A hemi-spherical dome of a building needs to be painted. IF the circum

1.	A hemi-spherical dome of a building needs to be painted. IF the circumference of the base of the dome is 17.6 m, find the cost of painting it, given the cost of painting is Rs. 5 per 100 cm2.
Answer» Circumference of a circle = 2πr Surface area of a hemisphere = 2πr² Given, base of the dome is 17.16 m ⇒ 2 × (22/7) × r = 17.6 ⇒ r = 2.8 m Surface area of the hemisphere = 2 × (22/7) × 2.8² = 49.28 m² = 492800 cm² Cost of painting is Rs. 5 per 100 cm², Cost of painting the dome = (492800/100) × 5 = Rs. 24640

A hemi-spherical dome of a building needs to be painted. IF the circumference of the base of the dome is 17.6 m, find the cost of painting it, given the cost of painting is Rs. 5 per 100 cm2.

Answer»

Circumference of a circle = 2πr

Surface area of a hemisphere = 2πr²

Given,

base of the dome is 17.16 m

⇒ 2 × (22/7) × r = 17.6

⇒ r = 2.8 m

Surface area of the hemisphere = 2 × (22/7) × 2.8²

= 49.28 m²

= 492800 cm²

Cost of painting is Rs. 5 per 100 cm²,

Cost of painting the dome = (492800/100) × 5

= Rs. 24640