A regression line contains the point (21.02, 35.5). The slope of the regression line is approx 3.1. What is the equation of the regression line?

Question

answer choices are:

a. y=3.1x-35.5

b. y=3.1x+35.5

c. y=3.1x-29.66

d. y=3.1x+21.02

Answer 1

Put the given information into the point-slope form of the equation of a line:

   (y-y₁) = m(x-x₁)       where m=slope and (x₁,y₁) is a point on the line

 

  (y-35.5) = 3.1(x-21.02)           [plug in values]

   y-35.5 = 3.1x - 65.162             [distribute]

      y = 3.1x - 29.662            [add 35.5 to each side]

Answer 2

(Y -- 35.5) / (X -- 21.02) = 3.1  Now solve for Y; therefore, Y = 3.1( X -- 21.02) + 35.3, which gives Y = 3.1X --29.66.  This will cross the y-axis at --29.66, and the X-axis at about 9.57