A cylindrical roller of radius 8 m and height 20 m is to be painted. The ends are to be painted in red and the curved surface is to be painted in blue. If the cost of painting in red is $₹ 2.1 p e r m^{2}$ and the in blue is $₹ 1.4 p e r m^{2}$ , what is the total cost of painting?

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Solution

The correct option is C
18

Given, $r = 8 m, h = 20 m$

Curved surface area $= 2 π r h = 2 \times π \times 8 \times 20 320 π m^{2}$

Area of the circular ends $= 2 π r^{2} = 2 \times π \times 8 \times 8 = 128 π m^{2}$

Cost of painting in red $= 2.1 \times 128 \times \frac{22}{7} = ₹ 844.8$

Cost of painting in blue $= 1.4 \times 320 \times \frac{22}{7} = ₹ 1408$

Total cost = 844.8 + 1408 = ₹ 2252.8

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A cylindrical roller of radius 8 m and height 20 m is to be painted. The ends are to be painted in red and the curved surface is to be painted in blue. If the cost of painting in red is ₹ 2.1 per m2 and the in blue is ₹ 1.4 per m2, what is the total cost of painting?

The correct option is C 18 Given, r=8 m, h=20 m Curved surface area =2πrh=2×π×8×20320π m2 Area of the circular ends =2πr2=2×π×8×8=128π m2 Cost of painting in red =2.1×128×227=₹ 844.8 Cost of painting in blue =1.4×320×227=₹ 1408 Total cost = 844.8 + 1408 = ₹ 2252.8

A cylindrical roller of radius 8 m and height 20 m is to be painted. The ends are to be painted in red and the curved surface is to be painted in blue. If the cost of painting in red is $₹ 2.1 p e r m^{2}$ and the in blue is $₹ 1.4 p e r m^{2}$ , what is the total cost of painting?