Answer:
 about 154 square feet
Step-by-step 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 2Ï€r, or 14Ï€ feet -- about 44 feet.
