12.03 Line plots
Are you ready?
Can you read information from a picture graph?
A poll was taken to find people's favorite cupcake flavors. The votes are shown in the picture graph.
| Cupcake Flavors | Number of People |
|---|---|
| Strawberry |  |
| Chocolate | |
| Vanilla | |
| Chocolate Chip | |
| Banana | |
Where represents $3$3 votes.
How many people voted for Strawberry?
What was the most popular cupcake flavor?
Chocolate chip
AStrawberry
BBanana
C
Learn
A line plot is similar to a picture graph, but using dots rather than images to show the number of values. They are also usually drawn with the dots stacked vertically, while picture graphs are often shown horizontally.
Let's look at an example. A set of measurements (in inches) have been taken, with the results recorded in the table below:
| $25$25 | $26$26 | $30$30 | $28$28 | $25$25 | $27$27 |
| $27$27 | $27$27 | $29$29 | $25$25 | $28$28 | $30$30 |
| $28$28 | $25$25 | $27$27 | $29$29 | $27$27 | $26$26 |
To make a line plot, we start by counting up the number of times each measurement appears. For this table, we have:
- $4$4 measurements of $25$25
- $2$2 measurements of $26$26
- $5$5 measurements of $27$27
- $3$3 measurements of $28$28
- $2$2 measurements of $29$29
- $2$2 measurements of $30$30
We can now plot the number of dots at each value on the line plot:
Apply
Question 1
Laura has a collection of juggling balls of different sizes. She measured the diameter of her juggling balls to the nearest inch, recording the values in the table below.
| $2$2 | $4$4 | $3$3 | $4$4 | $2$2 | $3$3 | $3$3 |
| $2$2 | $3$3 | $2$2 | $3$3 | $3$3 | $3$3 | $3$3 |
Which of the following line plots correctly shows Laura's measurements?
A
B
C
D
Learn
We can also use line plots to more easily understand key features of a data set. For instance, from a line plot we can clearly see which value is the most common by looking at which value has the most dots. We can also see the largest and smallest values in the data set.
Apply
Question 2
Elizabeth has $10$10 colored pencils in her pencil case. Some are shorter than others, depending on how much she has used them. The lengths of the pencils are shown in the line plot below.
How long is the shortest pencil Elizabeth owns?
How long is the longest pencil Elizabeth owns?
Line plots are a way to represent sets of data visually. By grouping the values together, line plots can make it easier to see key features of the data set.