In exercise 3, the following estimated regression equation based on 30 observations was presented. y = 17.6 + 3.8x1 – 2.3x2 + 7.6x3 + 2.7x4 the values of sst and ssr are 1805 and 1760, respectively. a. compute r2.b. compute r2a. c. comment on the goodness of fit.