Question

A closed cylindrical petrol storage tank that is 4.2m in Diameter and 4.5m in height. Find how much steel was actually used,if 1/12 of the steel actually used was wanted in making the tank

answer quick pls..​

Answer 1

Answer:

Step-by-step explanation:

Radius of the tank (r) = 4.2/2 m = 2.1 m

Height of the tank (h) = 4.5 m

Curved surface area = 2πrh m2

= (2 × 22/7 × 2.1 × 4.5) m2

= 59.4 m2

(ii) Total surface area of the tank = 2πr(r + h) m2

= [2 × 22/7 × 2.1 (2.1 + 4.5)] m2

= 87.12 m2

Let x be the actual steel used in making tank.

∴ (1 - 1/12) × x = 87.12

⇒ x = 87.12 × 12/11

⇒ x = 95.04 m2