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 as 50 paise per square decimeter 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» Given, Height of tank = 6 × radius of tank Let radius of tank = r decimeter So, height of tank = 6r dm Total surface area of tank = \(\cfrac{198\times100}{50}\) dm² = 2πr(h + r) = 198 × 2 = 2πr(7r) = 396 = r² = \(\cfrac{396\times7}{14\times22}\) = 9 r = 3 dm Height = 6r = 6 × 3 = 18 dm So, volume of tank = πr²h = \(\cfrac{22}7\times\)9\(\times\)18 = 509.14 dm³

The cost of painting the total outside surface of a closed cylindrical oil tank as 50 paise per square decimeter 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»

Given,

Height of tank = 6 × radius of tank

Let radius of tank = r decimeter

So, height of tank = 6r dm

Total surface area of tank = \(\cfrac{198\times100}{50}\) dm²

= 2πr(h + r) = 198 × 2

= 2πr(7r) = 396

= r² = \(\cfrac{396\times7}{14\times22}\) = 9

r = 3 dm

Height = 6r = 6 × 3 = 18 dm

So, volume of tank = πr²h = \(\cfrac{22}7\times\)9\(\times\)18 = 509.14 dm³