WAEC 2024 · Paper 2 · Q3

Plane mensuration

A circular floor of a building is to be tiled with square ceramic tiles, each of side $40\text{ cm}$ . If the perimeter of the floor is $66\text{ m}$ , calculate, correct to the nearest whole number, the number of tiles required to completely tile the floor. $\left[\text{Take } \pi = \frac{22}{7}\right]$

Worked solution (try it first)

(a)

The perimeter of the floor is its circumference: $2 \times \frac{22}{7} \times r = 66$ , so $r = 10.5$ m.
Area of the floor $= \frac{22}{7} \times 10.5^2$
$= 346.5\text{ m}^2$ .
Each tile is $40\text{ cm} = 0.4$ m square, so its area is $0.4 \times 0.4 = 0.16\text{ m}^2$ .
Number of tiles $= \frac{346.5}{0.16} = 2165.6$ , which is 2166 tiles to the nearest whole number.

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