Question

The cost of painting the total outside surface area of a closed cylindrical oil tank of at the rate of 50 Paisa per square metre is 198 the height of the tank is 6 times the radius of the tank find the volume of the tank

Answer 1

Total cost of painting the TSA =Rs198

Cost of painting 1 m^2 = 50 paise

= Rs 1/2

Total cost of painting the TSA = TSA × cost of painting 1 m^2

So, 198 = TSA × 1/2

TSA = 198 × 2

= 396 m^2

Let the radius of the tank be y

So, height of tank = 6y

TSA of tank = 2πr(r+h)

396 = 2 × 22/7 × x (y +6y)

396 = 44/7 × y ×7y

396 = 44 × y^2

y^2 = 396/44

y^2 = 9

y = 3

So, radius = 3m

And height = 6×3 = 18 m

Volume of tank = πr^2h

= 22/7 × 3× 3 × 18

= 509 m^3 (approx.)

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