1. Measures of location: The Mode and Modal Class
The mode is the most frequently occurring value in a set of data. Alternatively, if the data have been grouped as in a modal class, you can only estimate the mode. Usually, the stating boundaries of the modal class is sufficient.
The modal class for a grouped frequency distribution is the class with the highest frequency density.

2. The median is preferable to the mean when there are outliers.
Comparison of the mean, median and mode.
The median is preferable to the mean when there are outliers.
If there are outliers, the mean causes the frequency distribution to be skewed. See page 33 of your text book.
A distribution which has a tail of low values on the left, will have a mean which is less than the median.
Conversely, a tail of high values on the left, will have a mean that is greater than the median.

3. Now do Exercise 2C. 