To control Eurasian milfoil and other invasive aquatic weeds, the chemical herbicide 2.4-Dichlorophenoxyacetic acid (2,4-D), which is a synthetic auxin, is often applied to lakes in the midwest. A housing development is being built around a recently treated lake. The homes have individual wells tapping into the local aquifer. One week after the 2,4-D treatment, samples of water from 20 wells were analyzed for the presence of 2,4-D. Data were collected on 2,4-D per liter (in micrograms) of well water (Y) and the distance (in meters) of the wells from the edge of the lake (X) for 20 wells. The fitted regression line is Y = 500 - 2.5X. The estimated standard error of the least squares estimate of slope is 0.1 and Pearson's correlation coefficient r = -0.9. 11. What is the estimated intercept of the regression line? 12. What is the 95% confidence interval for the slope of the population regression line? 13. What is the value of the coefficient of determination R2? 14. What proportion of the variability in observed values of the 2,4-D level is not explained by the simple linear regression model? 15. For a well that is 1 meters from the lake's edge, what value of 2,4-D level would you predict using the regression line