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WAEC Mathematics 2017 Paper

Question : 35

Total: 49

\; \frac{22}{7}

]

Solution:

Concept:

The path is a ring around the pond. Its area is the difference between the area of the larger circle (pond + path) and the area of the pond.

Explanation:

Outer radius of the path = radius of pond + width of path.

Outer radius =

4\mathrm{m} + 2.5\mathrm{m} = 6.5\mathrm{m}

Area of the larger circle (pond + path) =

\pi r^2 = \frac{22}{7} \times (6.5)^2

\frac{22}{7} \times 42.25 = 132.7857... \approx 132.79\mathrm{m}^{2}

Area of the pond =

\pi r^2 = \frac{22}{7} \times (4)^2

\frac{22}{7} \times 16 = 50.2857... \approx 50.29\mathrm{m}^{2}

Area of the path =

132.79\mathrm{m}^{2} - 50.29\mathrm{m}^{2} = 82.50\mathrm{m}^{2}

Answer:

82.50\mathrm{m}^{2}

Correct option: D.

82.50\mathrm{m}^{2}

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