cost of painting the total outside surface of a closed cylindrical oil tank at 60 paise per sq dm - Maths - Surface Areas and Volumes

Question

cost of painting the total outside surface of a closed
cylindrical oil tank at 60 paise per sq dm is rs 237 60 the heigth
of the tank is 6 times the radius of the base of tank find its
volume correct to two decimal point ? and is que in easy

Lalit Mehra · Accepted Answer

@AJ_Hk278: Good answer! Keep posting!

Let r and h be the radius and height of the cylindrical tank.

Given, h = 6r

Total surface area of the closed cylindrical tank

$= 2 π r (r + h) = 2 π r (r + 6 r) = 2 \times \frac{22}{7} \times r \times 7 r = 44 r^{2}$

Cost of painting = 60 paise/dm² = Rs 0.6/dm²(Given)

Cost of painting 1 dm² = Rs 0.6

∴ Cost of painting 44r² dm² = Rs 0.6 × 44r²

Total cost of painting the closed cylindrical tank = Rs 237.60 (Given)

$∴ 0.6 \times 44 r^{2} = 237.60 \Rightarrow r^{2} = \frac{237.60}{44 \times 0.6} \Rightarrow r^{2} = 9 \Rightarrow r = 3$

Radius of the cylindrical tank = 3 dm

Height of the cylindrical tank, h = 6r = 6 × 3dm = 18 dm

∴ Volume of the cylindrical tank $= π r^{2} h = \frac{22}{7} \times (3 dm)^{2} \times 18 {dm = 509.14 dm}^{2}$ (Upto two decimal places)

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cost of painting the total outside surface of a closed cylindrical oil tank at 60 paise per sq. dm is rs.237.60 . the heigth of the tank is 6 times the radius of the base of tank . find its volume correct to two decimal point...? and is que. in easy