Please answer the following questions. They will give you a deeper insight into why a box and whisker plot is important.
What does IQR stand for?
What is it used for?
How is it calculated?
Why is it preferred over the range?
How can you use it to find outliers in your data?
Use the IQR to find the outlier in the data found on page 31 of your textbook.
and now you know, and knowing is half the battle!