Government agencies carefully monitor water quality and its effect on wetlands (reference: environmental protection agency wetland report epa 832-r-93-005). of particular concern is the concentration of nitrogen in water draining from fertilized lands. too much nitrogen can kill fish and wildlife. twenty-eight samples of water were taken at random from a lake. the nitrogen concentration (milligrams of nitrogen per liter of water) was determined for each sample. what's the variable? is it qualitative or quantitative? what is the implied population?