The cost of painting the total outside surface of a closed cylindrical

1.	The cost of painting the total outside surface of a closed cylindrical oil tank at 50 paise per square decimetre is Rs 198. The height of the tank is 6 times the radius of the base of the tank. Find the volume corrected to 2 decimal places.
Answer» Let ‘r’ be the radius of the tank. As per given statement: Height (h) = 6(Radius) = 6r dm Cost of painting for 50 paisa or Rs \(\frac{1}{2}\) per dm² = Rs 198 ⇒ 2πr(r + h) x \(\frac{1}{2}\) = 198 ⇒ 2 x \(\frac{22}{7}\) x r(r + 6r) × \(\frac{1}{2}\) = 198 ⇒ r = 3 dm And, h = (6 x 3) dm = 18 dm Now, Volume of the tank = πr²h = \(\frac{22}{7}\) x 9 x 18 = 509.14 dm³

The cost of painting the total outside surface of a closed cylindrical oil tank at 50 paise per square decimetre is Rs 198. The height of the tank is 6 times the radius of the base of the tank. Find the volume corrected to 2 decimal places.

Answer»

Let ‘r’ be the radius of the tank.

As per given statement:

Height (h) = 6(Radius)

= 6r dm

Cost of painting for 50 paisa or Rs \(\frac{1}{2}\) per dm² = Rs 198

⇒ 2πr(r + h) x \(\frac{1}{2}\) = 198

⇒ 2 x \(\frac{22}{7}\) x r(r + 6r) × \(\frac{1}{2}\) = 198

⇒ r = 3 dm

And, h = (6 x 3) dm = 18 dm

Now,

Volume of the tank = πr²h

= \(\frac{22}{7}\) x 9 x 18

= 509.14 dm³