A solid metallic rectangular block off dimensions 112cm × 44cm × 25cm is melted and recast into a cylinder of radius 35 cm. The curved surface area (in cm2) of the cylinder is: (Take π =22/7)
Show answer & explanation
Correct answer: C
Explanation
The correct answer is option 3 i.e. 7040
The volume of a cuboid = l × b × h
The volume of a cylinder = π × r2 × h
The curved surface area of a cylinder = 2 π × r × h
According to the question,
l × b × h = π × r2 × h
⇒ 112 × 44 × 25 = (22/7) × 35 × 35 × h
⇒ h = (112 × 44 × 25)/[(22/7) × 35 × 35]
⇒ h = 32
So, the height of the cylinder = 32 cm
Curved Surface area of cylinder = 2 π × r × h
⇒ Curved Surface area of cylinder = 2 × (22/7) × 35 × 32 = 44 × 160 = 7040 cm2