To find the upper quartiles y-axis value multiply the maximum cumulative frequency by ¾. To present this information on a pie chart use the. Since the number of values is an even number this means that there is no single middle value so we will need to locate the two middle values.
For the supermarket example the total number of observations is 200.
To find the lower quartiles y-axis value take the maximum cumulative frequency and multiply by ¼. It is the area of the bar that tells us the frequency in a histogram not its height. The Period goes from one peak to the next or from any point to the next matching point. Heres a handy formula for calculating the relative frequency of a class.