Desmos - Best Fit Line

Step 1 - Enter the Slope-Intercept Equation

Remember, the general equation for linear is y = mx + b

When you type these, you have to enter them in a special way since our best fit line is not going to go EXACTLY through the dots.

Since my table says x1 and y1 at the top, I'm going to type y1~mx1+b.

This is the same as the general line formula, but the ~ symbol tells it our line is approximate, and the x1 and y1 tell it to use the table!

Step 2 - What the heck does that mean?!?

After typing this, notice it graphs the best fit line automatically. It also pops up a box full of crazy letters and numbers!! Here are the important ones:

r is a measure of how strong your correlation is, and how well the line fits. The closer to 1, the better the fit. Its sign will also tell you whether it is a positive or negative correlation. So 0.9702 is a really strong positive correlation!
m = 70.5769 is the slope of the best fit line
b = 868.077 is the y-intercept of the best fit line (see it on the graph?)
So the equation of the best fit line (purple) is y=70.58x+868.08
- The 70.58 would be the approximate increase in profits each week
- The 868.08 would be the approximate profit in week 0 (the initial week)

SAVE YOUR WORK!!!

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