9514 1404 393
Answer:
8677.7 in² ≈ 60.3 ft² ≈ 5.6 m²
Explanation:
The area in square inches is the product of the circumference at the centerline of the border and the width of the border. The diameter of the pond is 3 m, about 3/0.0254 ≈ 118.110236 in. The centerline of the border has a diameter 20 inches more than that, about 138.110236 inches.
Then the area of the border is ...
A = Cw = πdw = (π·138.110236 in)(20 in) ≈ 8677.7 in²
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In square feet, this is about ...
(8677.7 in²) × (1 ft²)/(144 in²) ≈ 60.3 ft²
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In square meters, it is about ...
(8677.7 in²) × (1 m²)/(1550.0031 in²) ≈ 5.6 m²
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Additional comment
When the units of the question are mixed, it isn't clear if there's a typo. It also isn't clear what units are expected when the answer is supposed to be rendered to a precision of 1 decimal place.