The box-and-whisker plot is a graphical method for showing the median, quartiles, and extremes of data.

An example of a box-and whisker plot is shown below. Remember when finding the median, identify the middle number which is easy if the data set contains an odd number of items, but when there is an even number of items you must add the two middle numbers together then divide by two to find the median. The lower and upper quartiles represent the middle value between the median and the minimum and maximum values. Again this is easy when dealing with an odd number of items, but when you have an even number of items follow the same process for identifying the median when you have even numbers of data.

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