Suppose I want a field of 30 yards. If you are just messing around with folks you don't want to be running 100 yards to score. I don't know if my yard is 30 yards long, but let's say it is. Now, how wide should it be? The real deal is 53 1/3 yards. So mine should be the solution to
100 : 53 1/3 = 30 : x
It actually works out cleaner solving it with fractions. Anyway, x = 16 yards.
For the area, I have 30x16 = 480 square yards. However, I need this in square feet. There are 9 square feet in a yard, so 480x9 = 4,320 square feet. This could get a little expensive.
The cost, y would be found with 100 : 95 = 4,320 : y
So, y = $4,104. Also, I would have to somehow get yard markers, etc painted it. Still, it might be worth it.
Below is a picture of the field in Canton. (Hard to get a good picture from ground level.)