# Help

#### 1NAMILL

##### New Member
I'm having a little trouble with the following question:

Four pairs of data yield r = 0.942 and the regression equation (predicated value of y =3x. Also, the mean of y=12.75. What is the best predicted value of y for x=2.6?

Can you help? I'm not sure what formula to use. I'm trying to figure out if I'm suppose to use the regression equation. However, I don't know how to find the slope and y-intercept.

Thanks,

#### JohnM

##### TS Contributor
If the predicted value of y = 3x, then for x=2.6, y = 3*2.6 = 7.8

If in fact y=3x is the regression equation, then the slope = 3, and y-intercept=0

(in general, the regression equation is y = b + ax, with y-intercept b and slope a)

#### 1NAMILL

##### New Member
John,
Thanks, I got 7.8. However, I'm still not sure what formula to use. In the question it gives r = 0.942 and the mean of y to be 12.75. How do I incorporate thoses values in the equation since the predicted value of y is now 7.8?

#### JohnM

##### TS Contributor
Now I'm a bit confused about what the question is asking for.... Could you post exactly how the entire question is worded?

Thanks,
John

#### 1NAMILL

##### New Member
Here is the question again:

Four pairs of data yield r = 0.942 and the regression equation (predicted value of y =3x. Also, the mean of y=12.75. What is the best predicted value of y for x=2.6?

Last edited:

#### JohnM

##### TS Contributor
The best predicted value of y for x=2.6 is 3*2.6 = 7.8

Sometimes they will give you irrelevant info in the question to see if you can cut through the nonsense and answer the question.....

#### 1NAMILL

##### New Member
Thanks John. I got confused with all the extra stuff.