CanadaON
Grade 9

# Create and interpret scatter plots I

Lesson

A scatterplot is a different type of graph to many we have been looking at. Let's break this into two parts.

## Why do we use scatterplots?

If we want to see if there is a relationship between two things, which we call variables, we could use a scatterplot. This video shows us how scatterplots help us find patterns or relationships between variables so we can make judgements or decisions about them.

## Creating a scatterplot

Just like other types of graphs, when you're making a scatterplot, you need to include:

• a title
• labels for both axes, including the units of measurement

Now this video will show us how we plot the data.

Remember!

Remember, we need to find the intersection between our two variables, and plot a point at that spot.

#### Worked Examples

##### Question 1

The scatterplot shows the height and weight of six students. Use the plot to answer the questions.

Loading Graph...

1. How tall is the student who weighs $42$42kg?

2. How tall is the tallest student?

##### Question 2

The scatterplot shows the height and number of storeys of six buildings. Use the plot to answer the questions.

Loading Graph...

1. How many storeys does the tallest building have?

2. Which of the following statements about the plot is true?

The tallest building has the least number of storeys.

A

The shortest building has more storeys than the tallest building.

B

The tallest building has the most number of storeys.

C

The shortest building has the most number of storeys.

D

The tallest building has the least number of storeys.

A

The shortest building has more storeys than the tallest building.

B

The tallest building has the most number of storeys.

C

The shortest building has the most number of storeys.

D

##### Question 3

The table shows the number of apples eaten per week and the number of visits to the doctor per year by six students.

Answer the following questions.

 Number of apples eaten per week Number of visits to the doctor per year $2$2 $3$3 $6$6 $8$8 $9$9 $12$12 $16$16 $12$12 $9$9 $6$6 $3$3 $0$0
1. Plot the six points on the graph. The first point has been plotted for you.

Loading Graph...

2. Sophia wants to visit the doctor as few times as possible each year. According to the plot, should she eat $2$2 or $12$12 apples per week?

$2$2

A

$12$12

B

$2$2

A

$12$12

B