00:01
Okay, so in this question, we want to find the regression equation for predicting final score for midterm score based on some given information.
00:08
Since we know it's a linear regression, it will be in the form y equals mx plus b.
00:13
We want to, we're going to set y to the predicted final score because we're trying to predict that, and then we're going to set x to the midterm score because we're trying to predict the final score from the midterm score.
00:33
So the first thing we're going to do is find m.
00:37
The gradient for m is the correlation coefficient times the standard deviation of y over the standard deviation of x so we're given that the correlation coefficient is 0 .6 and the standard deviation of y is the standard deviation of the final scores and we're given that to be 20 and the standard deviation of x is a standard deviation of the midterm scores and we're given that to be 10 so the slope is 1 .2 that's what m is equal to so now we have y equals 1.
01:08
1 .2x plus b.
01:11
I'm going to make a new page real quick.
01:15
So just copying down that equation, y equals 1 .2x plus b.
01:18
And now we want to find what b is by plugging in that, plugging in a point.
01:23
And we know for sure that the average midterm and the average final.
01:28
That point is going to be on the regression because that's the definition of what a regression is...