In working further with the problem of exercise $4,$ statisticians suggested the use of the following curvilinear estimated regression equation.
$$\hat{y}=b_{0}+b_{1} x+b_{2} x^{2}$$
a. Use the data of exercise 4 to estimate the parameters of this estimated regression equation.
b. Use $\alpha=.01$ to test for a significant relationship.
c. Estimate the traffic flow in vehicles per hour at a speed of 38 miles per hour.