Question

The edges of three cubes of metal are 3 cm, 4 cm, and 5 cm. They are melted and formed into a single cube. Find the edge of the new cube. 

Answer 1

Volume of melted single cube = 3³ + 4³ +  5³ cm³ 
= 27 + 64 + 125 cm³ 
= 216 cm³ 

Let a be the edge of the new cube.
Volume  = 216 cm³ 
a³  = 216
a³  = 6³
a = 6 cm
Therefore, 6 cm is the edge of cube.