a To write an equation of the regression line, we first have to enter our ordered pairs into lists in our calculator. We can do this if we press the STAT button and then choose Edit.
Once the values have been entered, a regression can be performed by pressing the STAT button again, followed by the Right Arrow key to select CALC in the menu. This menu lists the various regressions that are available. If we choose LinReg, the calculator performs a linear regression test.
The regression line rounded to two decimal places can be written as follows.
y=1.18x+11
It has an approximate correlation coefficient of 0.72.
b Let's plot the residuals using our graphing calculator. To do this, you have to go to your STAT PLOT menu and choose the square plots. Use L1 for the Xlist and RESID for the Ylist. To graph the residuals, press 2nd followed by STAT, then choose RESID from the list of names.
The residuals seem to be randomly scattered and centered around the x-axis, which suggests that the regression fits the model well.
