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### Course: Statistics and probability>Unit 5

Lesson 3: Introduction to trend lines

# Estimating with linear regression (linear models)

A line of best fit is a straight line that shows the relationship between two sets of data. We can use the line to make predictions. To find the best equation for the line, we look at the slope and the y-intercept. Remember, this is just a model, so it's not always perfect!

## Want to join the conversation?

• For the second part of the question, could you just plug 3.8 into the equation? Isn't that what the question was asking, and not just to look off the graph?
• Yes. The question specifically asks you to use the equation, in which case the answer would be 96, not 97, but since the true values seem to be varying by up to about +/-10, 97 isn't too bad an estimate.
• there is a huge mistake in this video. the estimate is wrong., I typed in 97 and it turns out it was 96 and then I had to restart everything because of this answer !
• The estimate is anything near 97, it doesn't have to be 97 exactly because it is a estimate. The way I got exactly 96 was by plugging 3.8 for x in the equation.
• This video doesn't explain how to calculate plots that are not on the graph. How do we guess the future plots? What's the formula?
• You can find the equation of the line and just simply plug x variable in the equation.
• How can you exactly estimate this?
• You take your variable for x (in this case 3.8) and plug it into the equation you chose. Sal simply eyeballed it, but in order to be more accurate, you should work it out with the equation.
• ITS 96 ! all the trust i've built up for years.. where is it? GONE!
• it is a estimate it doesn't have to be exact, see I know that and my trust is unshaken.
• There are multiple complains on this, as for myself, do not understand this "simple" format.
• so weird that he wouldn't just plug 3.8 into the equation.....
• For the second part of the question, could you just plug 3.8 into the equation? Isn't that what the question was asking, and not just to look off the graph?
• yes, he just estimated it by looking at the graph, but yes, you should do that.
• In the next Practice lesson, Estimating equations of lines of best fit, and using them to make predictions, there is a multiple-choice question with 3 possible answers in y-intercept form. But the y has a ^ over it. Can anybody tell me what this means? Here's the link: https://www.khanacademy.org/math/cc-eighth-grade-math/cc-8th-data/cc-8th-line-of-best-fit/e/equations-of-lines-of-best-fit-to-make-predictions?modal=1