Question

The capacity of a closed cylindrical vessel of height 1 m is 15.4 litres. How many square metres of metal sheet would be needed to make it?

Answer 1

Here, h = 1 m, volume = 15.4 litres 

= 15.4/ 1000 m³ = 0.0154 m³ 

Also, volume of the cylinderical vessel = π r²h 

⇒ 0.0154 = 22/ 7 × r² × 1 

⇒ r² = 0.0154 × 7/ 22 = 0.0049

⇒ r = 0.07 m 

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

= 2 × 22/ 7 × 0.07 (1 + 0.07) m² 

= 44 × 0.01 × 1.07 m² = 0.4708 m² 

Hence, 0.4708 m² of metal sheet would be needed Ans.