Question

Three cubes of metal whose edges are $3$ cm, $4$ cm and $5$ cm, respectively are melted and a new cube is formed. The diagonal of the new cube is

• A. $4\sqrt{3}$ cm
• B. $6$ cm
• C. $6\sqrt{3}$ cm
• D. $8$ cm

Answer 1

Answer: (C)

$6\sqrt{3}$ cm

Side of the new cube $={(3^3+4^3+5^3)}^{1/3}={\left(216\right)}^{1/6}=6$
Diagonal $=\sqrt{3}\times side=6\sqrt{3}$ cm