Question

Find the lateral curved surface area of a cylindrical petrol storage tank that 4.2m in diameter and 4.5 metre height. How much steel was actually used if 1/12 of steel actually used was wasted in making the closed tank?​

Answer 1

Solution :-

Height of tank = 4.5 m

Diameter = 4.2

Therefore ,

Radius = 4.2/2 = 2.1m

CSA of Cylinder = 2πrh

CSA of cylinder = 2 * 22/7 * 2.1 * 4.5 = 59.4 sq.m

Hence , CSA of cylinder = 59.4 sq.m

Now , TSA of cylinder = 2πr( r + h)

TSA of cylinder = 2 * 22/7 * 2.1 ( 2.1 + 4.5)

TSA of cylinder = 2 * 22 * 0.3 * 6.6

TSA of cylinder = 87.12 sq.m

• Let the amount of steel used in making tank be x

Steel wasted = x/12

According to the question ,

Amount of steel required - Amount of steel wasted = TSA of tank

x - x/12 = 87.12

12x - x/12 = 87.12

11/12x = 87.12

x = 87.12 * 11/12

x = 95.04 sq.m

Hence , 95.04 sq.m steel is used in making tank