IXL - Interpret lines of best fit: word problems (Algebra 1 practice)

For a career-fair project, Colleen is researching the amount of money restaurant workers make from tips. She asks local waiters and waitresses about the lengths of their shifts and the amount of money they earn in tips. This scatter plot shows her data along with the line of best fit.

The equation for the line of best fit is

8.9

According to the equation, which of these statements is true?

A typical waiter or waitress earns about $2 per hour in tips.

A typical waiter or waitress earns about $9 per hour in tips.

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Learn with an example

question

Emmy is the manager at Sagebrush Horse Rescue. To help plan the weekly schedules, she keeps track of how long it takes to feed the horses each day and the number of volunteers who help that day. This scatter plot shows the data she collected and the line of best fit.

The equation for the line of best fit is

–

According to the equation, which of these statements is true?

Each additional volunteer decreases the time it takes to feed the horses by about 48 minutes.

Each additional volunteer decreases the time it takes to feed the horses by about 4 minutes.

key idea

A line of best fit roughly describes the relationship between two variables in a set of data. You can use a line of best fit to make predictions from a scatter plot.

The equation for a line of best fit can be written in the form

The slope is
m
.
It represents the predicted rate of change.
The
y
-intercept
is
b
.
It represents the predicted
y
-value
when
x
=
0
.

solution

The equation for the line of best fit is

–

It is in the form

–

is the predicted rate of change.

Write the predicted rate of change with units. The units on the

-axis

are minutes, and the units on the

-axis

are volunteers.

change in y

change in x

–

minutes

volunteer

The rate is -4 minutes per volunteer. Since the rate is negative, each additional volunteer decreases the time it takes to feed the horses by about 4 minutes.

Looking for more? Try these:

Lesson: Line of best fit

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Teacher tools

Work it out

Not feeling ready yet? These can help:

CC.12Evaluate a linear function: word problems

L.3Slope-intercept form: find the slope and y-intercept

II.6Make predictions with scatter plots

Lesson: Line of best fit

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