Problem 4)
We want to know the value of r when the speed (V) is 55 mph. So we'll plug in V = 55 and solve for r.
[tex]V = \sqrt{2.5r}[/tex]
[tex]55 = \sqrt{2.5r}[/tex]
[tex](55)^2 = \left(\sqrt{2.5r}\right)^2[/tex]
[tex]3025 = 2.5r[/tex]
[tex]\frac{3025}{2.5} = \frac{2.5r}{2.5}[/tex]
[tex]1210 = r[/tex]
[tex]r = 1210[/tex]
Therefore the radius of the curve is 1210 feet
