Answer : If a child's hyperactivity rating is predicted to be 18, he consumed 103.125 grams of food containing preservatives.
The regression (least-squares) equation given in the question is:
[tex] y = 1.5 + 0.16x [/tex]
In the equation above, y is the predicted variable. Here the predicted variable is the subjective hyperactivity rating (on a scale of 1 to 20).
The independent variable, x, is the quantity of food containing preservatives (in grams) consumed by hyperactive children.
The question tells us that the subjective hyperactivity rating of a child is 18.
Substituting the value of y in the equation above, we have,
[tex] 18 = 1.5 +0.16x [/tex]
[tex] \frac{16.5}{0.16} =x [/tex]
[tex] x = 103.25 [/tex]