II. Finding the models
a) Using the years as x and the life expectancy of males as y, enter the data in
paper, complete
the following steps:
your calculator in L1 and L2, respectively. Enter the life expectancy of females (as a second y list) in L3.
b) Set up the plots in your calculator so that you can display L1 and L2 as Plot1. Set
up Plot2 to display L1 and L3. [Recall that the setup for plots is done with 2nd Y=. Make sure that each plot uses a different mark so that you can distinguish between the two.] Use Zoom 9 to view the scatter plot, once you have set up the plots. Then adjust the window to match the grid on your graph paper. It should resemble the one you drew in part I.
*c) Using the Calculate menu under Stats, find a linear regression model for L1
and L2. Write the corresponding equation, showing accuracy to two
decimal places for a and b.
*d) Using the Calculate menu under Stats, find a linear regression model for L1
and L3. Note that the format will be LinReg (y=ax+b) L1,L3. Write the
corresponding equation, showing accuracy to two decimal places for a and b.
*e) Draw the two lines whose equations you found in parts c and d on the graph
you produced in part I. A simple way to do this is to find two points on each line
by substituting in values for x and solving for y. Use years that are actually on the
grid, i. e. between 1840 and 2000 and a multiple of 10. Do the lines appear to intersect? Where? Show approximate coordinates, based on the grid, as integers.