For this case we have that by definition, the area of a circle is given by:
![A = \pi * r ^ 2](https://img.qammunity.org/2020/formulas/mathematics/middle-school/aphz99i7s3sr0ed3hfa6uoaimn1hgptyrw.png)
Where:
r: It is the radius of the circle
We have as data that:
![r = \frac {42} {2} = 21 \ in](https://img.qammunity.org/2020/formulas/mathematics/middle-school/sn3mermprp0out1qatyfvh0zfrn86s71p4.png)
We found the table area:
![A = \pi * (21) ^ 2\\A = \pi * 441\\A = 1384.74 \ in ^ 2](https://img.qammunity.org/2020/formulas/mathematics/middle-school/7wtmzodm0b6p1qd7s50jqozhxahiwaiw89.png)
Now, we find the cost per square inch:
![\frac {280} {1384.74} = 0.22](https://img.qammunity.org/2020/formulas/mathematics/middle-school/kyepld60qgy2eezvjykno1wgh5utjxflmt.png)
Thus, the cost of the table is $0.20 per square inch.
ANswer:
The cost of the table is $0.20 per square inch.