9 The table shows information about the number of days absent last year by students in class 2A at a certain school.
| Number of days absent | 0 | 1 | 2 to 4 | 5 to 10 | 11 to 20 | 21 to 30 | More than 30 |
| Number of students | 7 | 12 | 9 | 1 | 0 | 1 | 0 |
- Calculate an estimate of the mean for these data.
- Find the median of these data.
The headteacher is writing a report on the numbers of absences at her school. She wishes to include a figure for the average number of absences in class 2A. A governor suggests that she should quote the mean. The class teacher suggests that she should quote the median, because it is lower than the mean.
- Give another reason for using the median rather than the mean for the average number of absences in class 2A.