trying to find the domain and the range of the functionsthe project is about scatter plots   years of 1980-2008   deaths from 16-90      

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embizze | High School Teacher | (Level 2) Educator Emeritus

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The domain of a relation (or a function) is the set of inputs. It is typically the independent variable, and is graphed along the x-axis.

If the data is listed as ordered pairs with year first followed by number of deaths (e.g. (1988,1267)) then the input is the year; the output is the number of deaths. If the data is the number of deaths by age per year, then the input is the age. It is unclear from your question how the data are listed.

So if the data is listed (year, number of deaths) then the domain is the set of years you are looking at:{1980,1981,...,2008}. If the data is listed as number of deaths per age (e.g.(16,134) means 134 people age 16 died) then the domain is the ages you are interested in: {16,17,...,90}

The range is the set of all outputs -- in either case above the range is the set of the different number of deaths.

If your data set is finite, then you can list both domain and range as sets. For a large data set, you can define the domain and range as intervals or inequalities: domain 1980<y<2008 with y a whole number year and the range as (smallest number of deaths)<d<(largest number of deaths) where d is a whole number of deaths.