WELLS 12.127 Arsenic in groundwater. Refer to the Environmental Science & Technology (January 2005) study of the reliability of a commercial kit to test for arsenic in groundwater, Exercise 12.16 (p. 710). Recall that you fit a first-order model for arsenic level (y) as a function of latitude (x1), longitude (x2), and depth (x3) to data saved in the file. Conduct a residual analysis of the data. Based on the results, comment on each of the following: a. assumption of mean error = 0 b. assumption of constant error variance c. outliers d. assumption of normally distributed errors e. multicollinearity