This is a linear regression problem. We are given the linear regression equation already, and that is [tex]\hat{y\:}=8.12-0.323x[/tex]. So, we are asked to find the value of y, when the value of x is equal to 5.
To do this, we just need to substitute the value of x to the given linear regression equation. That is
[tex]\hat{y\:}=8.12-0.323\left(5\right)=6.505[/tex]
Therefore, when the value of x is 5, the value of y is predicted to be about 6.5.