A **box plot** is a type of plot that displays the five number summary of a dataset, which includes:

- The minimum value
- The first quartile
- The median value
- The third quartile
- The maximum value

A typical box plot looks like this:

Within a box plot:

- The
**first quartile**represents the**25th percentile**of all values in the dataset. - The
**median**represents the**50th percentile**of all values in the dataset. - The
**third quartile**represents the**75th percentile**of all values in the dataset.

The **interquartile range** tells us the spread of the **middle 50% of values** in a dataset and can be calculated by subtracting the first quartile from the third quartile in a box plot:

The following example shows how to use a box plot to answer questions related to percentages.

**Example: How to Interpret Box Plot Percentages**

The following box plot shows the distribution of final exam scores for college students in a certain class:

Use the box plot to answer the following questions.

**Question 1: What percentage of students scored below a 70?**

From the box plot we can see that 70 lines up with the first quartile, which represents the 25th percentile.

Thus, **25%** of students scored below a 70.

**Question 2: What percentage of students scored above a 90?**

From the box plot we can see that 90 lines up with the third quartile, which represents the 75th percentile.

Thus, **25%** of students scored above a 90.

**Question 3: What percentage of students scored between a 70 and a 90?**

From the box plot we can see that 70 and 90 represent the first and third quartiles of the dataset, which correspond with the 25th and 75th percentiles.

Thus, 75% – 25% = **50%** of students scored between a 70 and 90.

**Additional Resources**

The following tutorials provide additional information about box plots:

Box Plot Generator

How to Compare Box Plots

How to Identify Skewness in Box Plots