In late may, 2016, lake mead, which supply water for 25 million people in nevada, arizona, and california, sank to its lowest level of 1,072 since the reservoir was filled in the 1930s. however, in 1983 it was at full capacity at 1225 ft above sea level. note: in 2019, lake mead is currently 40% of its full capacity. determine the rate of change in this situation.