Consider the given graph of the water temperature data for the eastern coast of the Gulf of Mexico.
We are not interested in a place or month in particular, so we can gather all the data for the water temperature.
84, 85, 86, 84, 84, 86, 85, 87, 87
82, 84, 84, 83, 85, 85
Let's use our graphing calculator to make a box-and-whisker plot of the data! We begin by organizing the data in a list. Press STAT, choose Edit, and enter all of the data into the first list.
Having entered the data, we can plot a box-and-whisker plot by pushing 2nd and Y= to choose STAT PLOT. Then, we will choose one of the plots in the list, turn the plot ON, and choose the type to be a box-and-whisker plot.
We will have to change the viewing window settings in order to see the plot. This can be done by pressing WINDOW and typing the new window settings.
Finally, we push GRAPH to draw the box-and-whisker plot.
In order to find the quartiles Q_1, Q_2 (which is the median), and Q_3, we can use the trace feature of our graphing calculator. We push TRACE and move the cursor to find each quartile.
We found the quartiles of the given data.
lQ_1=84 Q_2=85 Q_3=86
