Line of Best Fit and Trend Lines

Scatterplots and Trend Lines

8th Grade

What is a Trend Line?

When data is collected, points do not form a straight line, but they may approximate to a linear relationship

A trend line is a line that is

VERY CLOSE to most of the data points.

It is used to make conjectures (predictions)

Multiple Choice

What is a trend line used for?

• To make predictions

• To make the graph look pretty

• To connect the points

First, Lets make a trend line!

- Count the number of points, make a line that best fits the data points.

TIP: Count the number of total points. Try to have the same number of points on both sides of the trend line

Make a Prediction!

How many visitors would the beach have at 90 degrees?

Make a prediction!

What will the weight of the shipment be for 7 books?

Multiple Choice

Which graph shows a line of best fit (trend line) for the scatter plot?

• Graph A

• Graph B

• Graph C

• Graph D

Multiple Choice

Which of the following lines represents the line of best fit for the scatter plot?

• A
• B
• C
• D

Multiple Choice

Based on the scatterplot, what is the best prediction of the average number of hours a person spends at work every week, if that person spends an average of 10 hours on recreational activities every week?

• 33 hours
• 85 hours
• 50 hours
• 65 hours

Multiple Choice

Based on the scatterplot, what is the best prediction of the average amount of money spent on groceries for a household of 7 people?

• $240
• $190
• $210
• $300

The following questions are for you to do independently...

Multiple Choice

Based on the trend in the data, approximately how many free throws would a player be expected to make if he attempted 60 free throws?

• 50
• 35
• 25
• 60

Multiple Choice

Based on this scatterplot, approximately what score would a student with 6 absences expect to receive on the final exam?

• 65

• 92

• 67

• 76

Multiple Choice

Based on the scatterplot, about how much money would a group of 10 people be expected to spend on food and beverages at this restaurant?

• $135
• $115
• $105
• $150