Exercise 11 Page 206

We have been given a table with data for x and y.

x	0	1	2	3	4	5	6	7
y	- 8	- 5	- 2	- 1	- 1	2	5	8

In order to find a line of fit using our calculator, we need to first enter the values. Let's press the STAT button.

Then we choose the first option in the menu, Edit, and fill in the values in the lists L1 and L2.

Illustration of the lists on the calculator with six ordered pairs written

We can perform a regression analysis on the data by pressing the STAT button again, followed by using the right-arrow key to select the CALC menu.

This menu lists the various regressions that are available. If we choose the fourth option in the menu LinReg(ax+b) and press ENTER, the calculator performs a linear regression using the data that was entered.

Illustration of the LinReg(ax+b) window on the calculator

We can round the values of a and b and substitute them into the equation y= ax+ b. This gives us the equation for the line of best fit. y= 2.1x -7.5 We can see how the line fits with the data by plotting the data points and graphing the line on the same coordinate plane.

Scatter plot of the data with a line of fit

The calculator output gives us the value of the correlation coefficient, r. r=0.9803 ≈ 0.980 This tells us that correlation is positive and strong. We can tell that it is strong because it is extremely close to 1, which would be a direct correlation explained by a line that goes through all of the points.