Here’s the Quickest Way to Draw the Line of Best Fit

An Explanation of How to Draw a Line of Best Fit

Breaking Down the Line of Best Fit Definition

How to draw a Trend Line Practice Problems

Drawing a Line of Best Fit Video Explanation

Watch our free video on how to find the Line of Best Fit Equation. This video shows how to solve problems that are on our free Line of Best Fit worksheet answer key that you can get by submitting your email above. The video also explains the Line of Best Fit Definition in detail.

Watch the free Line of Best Fit video on YouTube here: Line of Best Fit

Video Transcript:

In this video we’re going to show you how to draw line of best fit by working on some of our practice problems from our line of best fit practice worksheet.

Let’s jump right in looking at number one on the writing equations for line of best fit worksheet. Our directions say write the equation of the lines of best fit in slope intercept form for each scatter plot. In order to do this the first thing we need to understand is that we’re talking about slope intercept form and our lines of best fit has to be written in that form. Slope intercept form is equal to y equals MX plus B. Typically this is the most common way you will see linear equations written. In the case of slope intercept form M is equal to the slope and B is equal to the y-intercept or where it crosses the y axis. If we look at number one, number one has a scatter plot drawn and it also has a lines of best fit already drawn through the scatter plot. If you look the easiest thing to identify is the y intercept that’s because all you have to do is see where the lines crosses the y axis, this vertical line here of course is the y axis and our lines of best fit crosses the y axis right there which is at 8.

We already know our y intercept which is 8, the next thing we have to find is our slope. Slope is equal to the rise divided by the run, so in order to find the rise divided by the run we have to find two points that are exactly on the line that intersect the grid perfectly. If we look we already have our first point which is our y intercept, so it’s already there. Then if you look really closely at our line you will see that you can pick points that cross the grid perfectly or where our line intersects the grid of the actual graph, so all these points actually intersect the line and the grid so right here. Then the next thing you need to do is you need to find the rise and the run so what we’re going to do is we’re going to go from one point to the next. So we’re just going to draw all lines and we’ll just do a couple there. What we do is we count how much we rise or drop and how much we go over. If we go down to so this is negative two because we’re going down two and if you look at each step each step is exactly the same down to so this negative two or this up-and-down motion is our rise. We know a rise is negative two then we have to find the run or how much we go over by. In case of this example we go over one here and we go over one here then we go over one here so a run is going to be one, and then if you simplify this negative 2 divided by 1 is just negative 2. So our slope is negative 2.

Then the last step is that you have to take each part which is slope and y-intercept and you have to substitute it back into slope intercept form. We know that our slope is negative 2 so we will substitute in negative 2 for M and then we know that y intercept is 8 so we will substitute an 8 for the y intercept. So our equation in slope intercept form for this lines of best fit is y equals negative 2x plus 8. These are just a couple example problems from the line of best fit practice worksheet that you can download above.