RRB Group-D Model Paper 14 with answers for online practice

We know that, volume of cube = ${\mathit{a}}^3$ (a is side of cube)
Given, cubes of sides 6 cm, 8 cm and 1 cm are melted to form a new cube
⇒ Volume of three cubes =
⇒ So, volume of new cube = 729 $\mathit{c}{\mathit{m}}^3$
⇒ Side of new cube = ${\left(729\right)}^{\frac{1}{3}}=9\mathit{c}\mathit{m}$
⇒ Surface area of new cube = $6{\mathit{a}}^2=6\times 9^2=486\mathit{c}{\mathit{m}}^2$