SSC CGL 2020 PYQ — Question 48

The correct answer is option 2 i.e. 256cm²

Let the length, breadth and height of a cuboid 'l' , 'b' and 'h'.

Length of the diagonal = 12.

$\sqrt{l^2 + b^2 + h^2}$ = 12

$l^2 + b^2 + h^2$ = 144.............(1)

l + b + h = 20 cm.

On squaring both sides we get,

l² + b² + h² + 2(lb + bh + hl) = 400

144 + 2(lb + bh + hl) = 400

2(lb + bh + hl) = 400 - 144 = 256cm².