Examine the following data:

a. Construct a scatter plot of the data. Determine the order of the polynomial that is represented by the data.
b. Obtain an estimate of the model identified in part a.
c. Conduct a test of hypothesis to determine if a third-order, as opposed to a second-order, polynomial is a better representation of the relationship between y and x. Use a significance level of 0.05 and the p -value approach.

r 28 9 12 15 22 2 25 37 39 y 4 75 175 415 620 7.830 7.551 7,850 11.12 11.617