Question

A hemispherical dome having a base diameter of 120 m is to be painted up to a point 30 m along the arc from the base. If one gallon of paint has a spreading capacity of 28.5 sq. m per coating, determine the number of gallons needed to paint the dome using 2 coatings

Answer 1

Hello mate!!





Solution:-

You have not mentioned about the unit of the circumference of the base of the dome. So, I have considered it in meters.

Circumference of circle = 2πr
⇒ 17.6 = 2*22/7*r
⇒ 44r = 17.6*7
⇒ r = 123.2/44
⇒ Radius = 2.8 m or 280 cm
Now, Curved surface area of the hemisphere = 2πr²
⇒ = 2*22/7*280*280
⇒ = 3449600/7
⇒ = 492800 sq cm
Cost of painting = Rs. per 100 sq cm
Total cost of painting = (492800*5)/100
Total cost of painting = Rs. 24640
Answer.




Hope it helpful