The independent variable here is b, the number of mats; the dependent var. is p, the cost of b mats. Thus, p = f(b).
Here, 245 units^3 = pi*r^2*(5 units), or
245 units^3
r^2 = ------------------- = 15.61 units^2. Thus, the radius is sqrt(15.61 units^2), or
5(3.14) units 3.95 units. The DIAMETER is d = 2*r = 7.90 units.
