Answer:
Option d.
Step-by-step explanation:
The equation of the line of least squares is given as
where is the yield of wheat (bushels per acre) and x is the rainfall (in inches).
We need to find the expected number of inches of rain if the yield is 60 bushels of wheat per acre.
Substitute in the given equation.
Add 9.12 on both sides.
Divide both sides by 4.38.
The expected number of inches of rain is 15.78.
Therefore, the correct option is d.