What is a box and whisker graph?

Answer 1

It is an oblong box with a vertical line partway along its length and a horizontal "whisker" sticking out in each direction. The graph is drawn with a horizontal numerical axis. The figure below gives a rough idea. The dots in the top left are not part of the box-and whiskers graph: they are there just for spacing.

............ ______

---------|___|_|------

a.........b.....c..d......e

a = minimum value (excluding outliers)

b = lower quartile

c = median

d = upper quartile

e = maximum value (excluding outliers).

If there are any outliers, they are shown as x beyond the ends of the whiskers.

Answer 2

A box and whisker graph is used to display a set of data

so that you can easily see where most of the numbers are.

First you write the data from smallest to largest. Then you find the median of all the numbers. This is called the main median.

Next you look at the numbers on either side of the median and find their median.

These are called the lower and upper medians. So you are just finding the median of a subset.

One subset is the numbers above the median and one is the numbers below the median.

Now, on the number line, make a mark for the main median and a mark for the upper and lower medians.

Next, draw a box with the median lines above as the endpoints. Really it looks like a box

with a line in the middle where the main median is. This is the BOX in the box and whisker graph.

Last, draw lines from the ends of the box to the smallest data point and largest data point on either side of the box.

These are the WHISKERS.

The graphs you made tells you the range of the data and it tells you where each quarter is.

The three medians split the data into 4 parts.