A five-number summary contains five pieces of information, and is one way of describing the distribution of data in a data set.
A box plot or box and whisker plot can be used to illustrate the distribution of a data set. A box plot has three parts.
A boxplot is a scaled figure, usually presented above a number line.
Thanks a Latte Café measured the temperature of cappuccinos. The box plot below shows the results in F.
A good cappuccino, according to the experts, has a temperature between F and F. Approximately how many of the cappuccinos could be considered "good"?
Each part of a box plot contains of the data. This means the box contains of the data.
The first quartile is located at degrees and the third is at degrees. This means that about of the cappuccionos were in the ideal temperature range. This gives Approximately cappuccinos can be considered "good".
Sometimes, the data will be given in ascending order. When it is not, it's necessary to order the data so the quartiles can be found. With an ordered data set, the minimum and maximum are easily identifiable. Here, the minimum is and the maximum is These are marked above a number line with a line segment, indicating the range.
Since there are values, the median is the mean of the numbers at the th and th position. Now, the median can be determined by calculating the mean of and The median is This is marked as a vertical line segment in the range. Remember that the line for the median falls inside the box.
The quartiles are marked as the sides of the box plot. Now the box plot is complete.