A hemispherical bowl has a 21 cm radius. It is to be painted inside as well as outside. The cost of painting it at the rate of ₹0.05 per cm
2
and assuming that the thickness of the bowl is negligible, is: (Use π=
7
22
)
- A₹410.10
- B₹188.30
- C₹277.20
- D₹388.20
Solution & Step-by-step Explanation
Radius (r) = 21cm
Since the bowl has negligible thickness and is painted both inside and outside, total area to be painted is equal to twice the inner curved surface area.
Total Area=2×(2πr
2
)=4πr
2
Total Area=4×
7
22
×21×21=4×22×3×21=5544cm
2
Cost of painting = Total Area×Rate=5544×0.05=₹277.20
Since the bowl has negligible thickness and is painted both inside and outside, total area to be painted is equal to twice the inner curved surface area.
Total Area=2×(2πr
2
)=4πr
2
Total Area=4×
7
22
×21×21=4×22×3×21=5544cm
2
Cost of painting = Total Area×Rate=5544×0.05=₹277.20