WAEC 2024 · Paper 1 · Q26

Solid mensuration

The length and breadth of a cuboid are $15\text{ cm}$ and $8\text{ cm}$ respectively. If the volume of the cuboid is $1{,}560\text{ cm}^3$ , calculate the total surface area.

Worked solution (try it first)

Find the height first: the base is $15 \times 8 = 120\text{ cm}^2$ , so $h = 1560 \div 120 = 13$ cm.
The three pairs of faces are $15 \times 8 = 120$ , $15 \times 13 = 195$ and $8 \times 13 = 104$ .
Total surface area: $2(120 + 195 + 104) = 2 \times 419$
$= 838\text{ cm}^2$ , option B.

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