SSC CHSL Model Paper 18

Total surface area of prism = Curved surface area + 2 × Area of base
⇒ 608 = Perimeter of base × height + 2 × Area of base
⇒ $608=4\mathit{x}\times 15+2{\mathit{x}}^2$
(When x = side of square)
⇒ ${\mathit{x}}^2+30\mathit{X}-304=0$
⇒ ${\mathit{x}}^2+38\mathit{x}-8\mathit{x}-304=0$
⇒ $\mathit{x}\left(\mathit{x}+38\right)-8\left(\mathit{x}+38\right)=0$
⇒ $\left(\mathit{x}-8\right)\left(\mathit{x}+38\right)=0\Rightarrow \mathit{x}=8$
Volume of prism = Area of base x height
$8\times 8\times 15=960{\mathrm{cm}}^3$