Find

(i) the lateral or curved surface area of a closed cylindrical petrol storage tank, which is 4.2 m in diameter and 4.5 m in high.

(ii) how much steel was actually used, if 1/12 of the steel actually used was wasted in making the tank?

(i) We have, cylindrical petrol storage tank having diameter, d = 4.2 mh = 4.5 m

(ii) Now, total surface area of cylindrical tank

Since, 1/12 of the actual steel used was wasted. Therefore, the area of the steel, which was actually used for making the tank