NECO 2022 · Paper 1 · Q37

Find the total surface area of the cuboid in the figure.

Worked solution (try it first)

A cuboid has three pairs of equal faces: $18 \times 5 = 90$ , $18 \times 3 = 54$ and $5 \times 3 = 15\text{ cm}^2$ .
One of each adds to $90 + 54 + 15 = 159\text{ cm}^2$ .
Double it for the pairs: $2 \times 159 = 318\text{ cm}^2$ , option D.