Answer:
about 154 square feet
Explanation:
The area of the pool is given by the formula for the area of a circle:
A = πr²
A = π(7 ft)² = 49π ft² ≈ 153.94 ft²
About 154 square feet of material will be needed to cover the top of the pool.
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Additional comment
The circumference of the pool is 2πr, or 14π feet -- about 44 feet.