Question

20 identical metallic cubes each of edge length 5cm are melted and the metal so obtained is used to create a cylindrical rod of base radius 4cm . What is the length of the rod ?

Answer 1

Area of one cube = 5² = 25 cm²
Area of 20 cubes = 20 * 25 = 500 cm²

Cylindrical rod :
Base radius = 4 cm
Area = 500 cm²
Area = π r² h
(22 / 7) * 4 * 4 * h = 500
⇒ h = 500 * 7 / 22 * 4 * 4
⇒ h = 9.94 cm or 62.5 / π

Answer 2

$50cm(approx) length of cylinder$