In the previous section, we estimated the average test score $\left(y\right)$ given the number of study hours $\left(x\right)$.
What if we want to estimate study hours $\left(x\right)$ based on average test score $\left(y\right)$?
Move the two black points to try to minimize the distance between the points and the line.
Click here (password: P3%8=B*C) to see how to find the regression line $x=my+b$ using your GDC.
Use your GDC to find the regression line $x=my+b$ (to 3 significant figures) $m=$
(to 3 significant figures) $b=$
So, the equation of the regression line (to 3 significant figures) is $x=$
Graph this line in the Desmos window above to see how close you were.
Since there is a strong correlation, it is reasonable to use this equation to estimate other values.
For example, using your equation $x=0.351y-12.6$, estimate the hours of study per week for a student who:
has an average test score of 50%. (to 3 significant figures)
has an average test score of 85%. (to 3 significant figures)
has an average test score of 10%. (to 3 significant figures)
hours
hours
hours
Clearly, the last estimate is unrealistic and unreliable because $y=10$ lies far outside the data points.
This is called
.