A medical student reads that with enough sun exposure, the human body can manufacture vitamin D3. This sounds too amazing to be true, so he decides to test it out. Over the next few weeks, he spends a varying number of hours in the sun, x. At the end of each week, he measures the concentration of vitamin D3 in his blood (in nanograms per milliliter), y. Find the equation for the linear regression model that fits the data.
Select one of the following: