Answer:
1.78 feet.
Step-by-step explanation:
If they cost $20 each and its $2 per square foot, the area of the spheres
is 20 / 2 = 10 ft^2.
Area of sphere = 4 π r^2 = 10 (where r = the radius)
---> r^2 = 10 / 4π
= 0.796
---> r = 0.892 ft
So the diameter = 2 * r
= 1.78 feet to nearest hundredth.