A five number summary in statistics is made up of a Minimum, Median, Maximum and Q1/Q3. Q1 and Q3 help you to find the interquartile range: an important factor in looking at the spread of data. When you create a box plot with whiskers on the TI-89, the TI-89 will automatically calculate the five number summary for you, saving you time and effort.
Sample problem: Create a boxplot and find the five number summary for the following data: 200, 350, 300, 350, and 400.
Step 1: Create a new folder called “Box.” From the Home screen, press F4 and scroll down to NewFold (option B). Press Enter.
Step 2: Enter 2nd Alpha ( – x to spell B O X and press Enter.
Step 3: Press Apps, then scroll down to Stats/List Editor. Press Enter twice.
Step 4: Press the down arrow key to get to the first line of the list. Enter your data into list1. Follow each entry with a comma: 200, 350, 300, 350, 400.
Step 5: Press F2, 1 to enter Plot Setup.
Step 6: Press F1, right arrow, and 5 to select mod box plot.
Step 7: Arrow down to Mark and select box.
Step 8: Arrow down and enter B O X in the x box. 2nd Alpha ( – x to spell B O X. Press Enter.
Step 9: Read the boxplot. Press F3 and use the left and right cursors to find Min(200), Q1(250), Med(325), Q3(400), and Max(500).
Tip: if you want to change the folder back to MAIN, press Mode, scroll down to Current Folder. Press right key, then press 1 Enter.
TipIf you get the error message undefined variable, it can be a frustrating process to try and solve the problem. Clearing the memory *may* help, but an easier way to get the box plot to graph is to enter the data into “list 1″ in the List Editor and then type “list 1″ as your “x” when defining the box plot.
Lost your guidebook? You can download a new one from the TI website here.