Question
Download Solution PDFA hemispherical bowl has a radius of 7 cm. It is to be painted from inside as well as outside. Find the cost of painting it at the rate of Rs.40 per 20 cm2? (Take thickness of the bowl as negligible).
Answer (Detailed Solution Below)
Detailed Solution
Download Solution PDFA hemispherical bowl has a radius = 7cm
The cost of painting it at the rate of Rs.40 per 20 cm2
Formula used:-
Curved Surface Area of Hemisphere = 2πr²
Calculation:-
Inside Surface Area = 2π(7 cm)² = 2 × 22/7 × 49 = 308 cm²
Outside Surface Area = 2π(7 cm)² = 308 cm²
Total Surface Area = Inside Surface Area + Outside Surface Area
Total Surface Area = 616cm²
The cost of painting this area at the given rate of Rs. 40 for 20 cm²
Cost = (Total Surface Area / 20 cm²) × Rs. 40
Cost = (616 / 20) × 40 = 1232 Rs.
∴The cost of painting both the inside and outside of the hemispherical Rs.1232.
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