A solid is composed of a cylinder with hemispherical ends. If the whole length of the solid is 104 cm and the radius of each of the hemispherical ends is 7 cm, find the cost of polishing its surface at the rate of Rs. 10 per dm².
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Total cost of polishing = Rs. 457.60
Step-by-step explanation:
Radius of the hemisphere = 7cm
Total length of solid = 104cm.
So height of cylinder = 104 - 2(7) = 90cm
Radius of the cylinder = 7cm
Curved surface area of cylinder = 2πrh
2 * Curved surface area of hemisphere = 4πr²
Total surface area = 4πr² + 2πrh = 2πr (2r + h)
= 2 * 22/7 * 7 (14 + 90)
= 4576 sq.cm
Cost of polishing the surface = 10 per dm² = 10/100 per cm² = Rs. 0.10
Total cost of polishing = 0.1 * 4576 = Rs. 457.60
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