Question

A data set consists of the following data points:

(3,5), (5,8), (6,13)

The slope of the best fit line is 2.5. Find the y-intercept of this line.

Answer 1

find xbar and ybar. the line goes through that point and has the given slope. from there you can write the point-slope form of the line and solve for y to get it into slope-intercept form and thus find the intercept

Answer 2

whats xbar ? and y \bar?

Answer 3

ybar

Answer 4

the averages of the x's & y's, respectively

Answer 5

okay... but how do i found the y intercept of 2.5?

Answer 6

xbar\[=\frac{ 3+5+6 }{ 3 }\]

Answer 7

do you remember linear equations? y = mx+b

Answer 8

sort of,

Answer 9

4.6 ?

Answer 10

so m is the slope and b is the y-intercept. the same will hold for regression lines except the data is used to get the slope and y-intercept

Answer 11

so that's xbar, find ybar

Answer 12

8.6

Answer 13

now you have the point (4.666666, 8.666666) and a slope of 2.5
the point-slope form of a line is \[\left( y-y _{1} \right)=m \left( x-x _{1} \right)\]
where m is the slope (2.5 in this case) and the point is \[\left( x _{1}, y _{1} \right)\]

Answer 14

and whats the other x and y ?

Answer 15

put the numbers in their proper places and then solve for y. the equation will be in the slope-intercept form, i.e.,\[y=mx+b\]and whatever b is will be the intercept you seek

Answer 16

they are the variables and they stay

Answer 17

i dont get it,

Answer 18

how many x and y 's are there?

Answer 19

you should review linear equations...
have a look at this site:
http://www.mathsisfun.com/algebra/linear-equations.html

Answer 20

i dont have time for reviewing, :/ i need to pass this by tomorowwww. well thanks for helping anyway.

Answer 21

y−8.6=2.5(x−4.6)
solve for y and the y intercept will be the constant term (the one not multiplied by x)

Answer 22

so whats the answer???-.-