A Daniel cell uses zinc and copper solutions to produce electricity. An experiment was conducted to determine whether voltage (y) is affected by the temperature of the solutions (x1, °F), the...

A Daniel cell uses zinc and copper solutions to produce electricity. An experiment was conducted to determine whether voltage (y) is affected by the temperature of the solutions (x1, °F), the concentration of the solutions (x2, M), and/or the surface area of the electrodes (x3, cm2 ).

To keep golf courses attractive in the arid southwest, groundskeepers carefully monitor salt content in water used for irrigation. It is believed that high salt concentration can damage plants and grass. A random sample of golf courses in the southwest was obtained and a sample of water used for irrigating was obtained for each. The following variables were measured for each water sample: dissolved salt (y, dS/m), total dissolved solids (x1, mg/L), sodium, calcium magnesium, and bicarbonate (x2, x3, x4, and x5, all in milliequivalents/liter)