Question

It is required to make a closed cylindrical tank of height 1 m and base diameter 140 cm from a metal sheet. How many square metres of the sheet are required for the same?.

Answer 1

Here, h = 1 m, r = 140/ 2 cm = 70 cm = 0.7 m 

Total surface area of the cylinder = 2πr (h + r) 

= 2 × 22/ 7 × 0.7 (1 + 0.7) m² 

= 44 × 0.1 × 1.7 m² = 7.48 m² 

Hence, 7.48 m² of sheet is required Ans.