Ecology: wetlands 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 nitrogent can kill fish and wildlife. twenty-eight samples of water were taken at random from a lake. the nitrogen concentration (milliagrams of nitrogen per liter of water) was determined for each sample. a) identify the variable. b) is the variable quantitatie or qualitative? c) what is the implied population?

a) The variable of the study is: milligrams of nitrogen per liter of water.

This is the amount that needs to be measured and analyzed to reach conclusions in the study.

b) The variable is quantitative. The quantitative variables are those that represent quantities. This variables can be measured on a continuous or discrete scale. Then, all the variables that you can measure or count are quantitative variables(height of trees, number of passengers per car, wind speed, milligrams of nitrogen per liter, etc). On the other hand, qualitative variables are those that can’ t be measured, and they represent attributes, like apple colors (red, green), size of trousers (small, medium, large) and so on.

c) The population under study is the milligrams of nitrogen per liter of water that are in the entire lake. You can estimate the parameters of the population by taking samples (In the example, 28 samples are taken).

f(x) has value 150 at x= 0

and 0 at x= 3

so d(f(x))/dt = slope = -150/3 = -50