The Algebra Teacher\'s Guide to Reteaching Essential Concepts and Skills

Name Date

WORKSHEET 4.14: FINDING THE EQUATION OF THE

LINE OF BEST FIT

-------------------------------------------------------------------------------------

A line of best fit is a line that approximates a relationship between a group of ordered pairs.

Use the steps below to find the equation of the line of best fit:

1. Graph the ordered pairs to create a scatter plot.


2. Use a ruler to draw a line of best fit. Some points may be on your line and others may
   not.


3. Choose two points on the line you have drawn. Use the formulam=
   y 2 −y 1
   x 2 −x 1
   to find the
   slope of the line.


4. Find they-intercept by substituting thex-coordinate of one point, they-coordinate of
   the same point, and the slope in the formulay=mx+b.Thensolveforb.


5. Write the equation of the line of best fit in slope-intercept form.

DIRECTIONS: Find the equation of the line of best fit for the data below. Round to the

nearest tenth.

1. (3, 4), (2, 7), (5, 8), (6, 10), (4, 8), (5, 9.5), (8, 15), (1, 1.5), (8, 13), (3, 5)


2. (10, 6), (8, 4), (20, 10), (15, 12), (14, 12), (9, 4), (15, 10), (20, 15), (4, 3), (6, 5)


3. (1, 3), (1, 4), (1, 2), (2, 4), (2, 5), (3, 6), (3, 7), (3, 10), (4, 15), (4, 12)


4. (10, 5), (1, 0.75), (8, 5), (6, 4), (7, 3), (4, 1.5), (9, 4), (8, 6), (1, 1), (2, 1.5)

CHALLENGE:Michelledrewalineofbestfit.Butinsteadofchoosingpoints

on the line, she chose the first and last points of the data to write the

equation. Will her equation be very different from the equation she would

get if she had chosen two points on the line? Explain your answer.

165

Copyright

©

2011 by Judith A. Muschla, Gary Robert Muschla, and Erin Muschla. All rights reserved.