Answer:
4.0 feet
Explanation:
You want the diameter of a rubber ball that costs $1, if that cost is $0.02 per square foot.
Area
The surface area of a sphere is given by ...
A = 4πr²
In terms of diameter, this is ...
A = 4π(d/2)² = πd²
Cost
The cost will be ...
Cost = (cost/square foot)(area)
1.00 = 0.02(πd²)
Diameter
Solving for d, we have ...
d² = 1.00/(0.02π) ≈ 15.915
d ≈ √15.915 ≈ 3.989 ≈ 4.0 . . . . feet
The diameter of the ball is about 4.0 feet.
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