(15%)7. Based on a sample of 30 observations, the population regression model

$$Y_i = \beta_0 + \beta_1 x_i + \varepsilon_i$$

was estimated. The least squares estimates obtained

$$b_0 = 10.1 \text{ and } b_1 = 8.4$$

The regression and error sums of squares were

$$SSR = 128 \text{ and } SSE = 286$$

(a) Find and interpret the coefficient of determination.