1. Is there a graphical method for finding the quartiles in a set of data.
The quartiles and median can easily be found from a stem and leaf graph or a cumulative frequency graph, studied in more detail in Year 10, topic 49
2. Is there a formula for finding the quartiles in a set of data?
A formula which is very useful is:
Quartile depth =
where n is the number of values and when n/2 is found any halves are dropped.
Therefore, the lower quartile is the 3rd value from the bottom of the set of values.
The upper quartile is the 3rd value from the top of the set of values.
3. Is there a similar formula for finding the median in a set of data?
Yes, the formula for the median =
Therefore the median is the 6th value from either the top or from the bottom of the set of values.
