12.16 Arsenic in groundwater. Environmental Science & reliability of a commercial kit to test for arsenic in ground- @ Technology (January 2005) reported on a study of the WELLS water. The field kit was used to test a sample of 328 ground- water wells in Bangladesh. In addition to the arsenic level (micrograms per liter), the latitude (degrees), longitude (degrees), and depth (feet) of each well were measured. The data are saved in the file. (The first and last 5 observa- tions are listed in the table below.) Well ID Latitude Longitude Depth Arsenic 10 14 30 59 85 7353 1337 7890 7893 7970 23,7887 90.6522 60 331 23.7886 90.6523 45 302 23.7880 90.6517 45 193 23.7893 90.6525 125 232 23.7920 90.6140 150 19 23.7949 90.6515 40 48 237930 90.6515 30 172 23.7658 90.6312 6l) 175 23.7656 90.6315 45 624 23.7644 90.6303 30 254 . Write a first-order model for arsenic level (v) as a function of latitude, longitude, and depth. . Fit the model to the data using the method of least squares. . Give practical interpretations of the 8 estimates. . Find the model standard deviation, s, and interpret its value. Find and interpret the values of R* and R3. . Conduct a test of overall model utility at a = 035. Based on the results, parts d-f, would you recommend using the model to predict arsenic level (v)? Explain