Answer:
952 cubic feet
Explanation:
The diameter is 21, so the radius is 10.5. The area of a circle is πr^2, so 10.5^2π, or 110.25π. The pool is filled 9 inches from the top, so it is 3.5 feet - 9 inches high, 9 inches is 0.75 feet, so 2.75 feet filled. Now multiply 110.25π by 2.75 to get 303.1875π and then 952.4916, closer to 952 cubic feet.
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