A diameter of 4 feet would mean a radius of 2 feet, half that.
The area of a circle is [tex] \pi r^{2}[/tex]
2² = 2*2 = 4, so the table is 4π ft²
3² = 3*3 = 9, so the cloth is 9π ft²
9π cloth - 4π cloth on the table = 5π hanging over the edge.
We can approximate π to 3.14 and 5*3.14=15.7, so there is 15.7 ft² of cloth over the edge.