A storage tank consists of a circular cylinder with a hemisphere adjoined on either end. If the external diameter of the cylinder be 1.4 m and its length be 8 m, find the cost of painting it on the outside at the rate of Rs. 10 per m2.
Curved surface area of a cylinder = 2πrh
Curved surface area of hemisphere = 2πr2
Given, external diameter of the cylinder be 1.4 m and its length be 8 m
Thus r = 0.7m and h = 8m
Total curved surface area = 2πrh + 2πr2
⇒ Total curved surface area = 2 × (22/7) × 0.7 × 8 + 2 × (22/7) × 0.72 = 38.28 m2
Cost of painting it on the outside at the rate of Rs. 10 per m2 = 38.28 × 10 = Rs. 382.80
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