Even though nitrogen constitutes 78% of Earth's atmosphere, the amount available for living things nearly all comes from nitrogen-containing fertilizers. a few groups of nitrogen-fixing bacteria. the breakdown of dead plants. the breakdown of minerals. a few genera of detritivores.

Aresearcher created three groups based on participants bmi: normal weight, overweight and obese. the hypothesis being tested is that the three groups differ in the mean number of artificially sweetened drinks consumed weekly. which statistical test might the researcher use, assuming a reasonably normal distribution of values.