A hemispherical dome of a building needs to be painted. If the circumference of the base of the dome is 154 cm, then find the cost of painting it if the cost of painting is 4 per ₹100 cm2 (use ).
Show answer & explanation
Correct answer: A
Explanation
The correct answer is option 1 i.e. ₹150.92.
Circumference = 2πr = 154
⇒ 2 × (22/7) × r = 154
⇒ r = 49/2 = 24.5 cm
Curved surface area of a hemisphere = 2πr2 = 2 × (22/7) × (49/2)2 = 3773 cm2
Cost of painting = (3773/100) × 4 = 150.92
Hence, the cost of painting the hemispherical dome is ₹150.92.