Question

64 cubes of the side 5 cm are melted to form a new cube, the radius of the new cube is .

• A. 20 cm
• B. 15 cm
• C. 6 cm

Answer 1

The correct option is A 20 cm

Given: Radius of original cube = 5 cm
Number of cubes = 64
Let the side of the new cube = x

Volume of the cube = (Side)${}^3$
Volume of the original cube = $(5{)}^3=125c{m}^3$
Total volume of 64 cubes = 125 $\times 64$ = 8000 cm${}^3$
Volume of new cube = Total volume of 64 cubes
x${}^3$ = 8000
x = 20 cm