1. Box Plots
Example
A car park attendant makes a record every hour of the number of cars in the car park.
work out the median and quartiles for number of cars in the car park
Draw a box plot to represent this data.

2. Example
A gardening magazine sells seedlings of a plant through the post and claims that the average height of the plants after one years growth will be 85cm. A sample of 24 of the plants were measured after one year with the following results (in cm) 6 7 9 34 56 85 87 89 90 91 92 93 94 95 96 97 99
a) Find the median height of the sample
b) Find the Inter-quartile range for the sample
c) Represent this sample on a box and whisker plot

3. Example
The table shows the heights of thirty boys, correct to the nearest centimetre.
Height
145
146
147
148
149
150
151
152
153
154
Number of boys 2 1 3 5 7 4
a) Obtain the median height of these boys and their inter-quartile range
b) Represent these heights on a box plot