The company imports roses from Egypt. Equation: y = 450x + 2800 is a simple regression equation (X - price in PLN / unit, Y - monthly sale of roses in units), coefficient of determination R^2 = 0.85, linear correlation coefficient r = 0.92 (Pearson). Complete the sentences: a) Assess the expanation of the model to empirical data ...% the volatility of the monthly sale of roses was explained by ... b) With the price = 2 zlotys, the forecast monthly sale of roses will amount to ...