2 The numbers of absentees per day from Mrs Smith’s reception class over a period of 50 days are summarised below.
| Number of absentees | 0 | 1 | 2 | 3 | 4 | 5 | 6 | \(> 6\) |
| Frequency | 8 | 15 | 11 | 8 | 3 | 4 | 1 | 0 |
- Illustrate these data by means of a vertical line chart.
- Calculate the mean and root mean square deviation of these data.
- There are 30 children in Mrs Smith's class altogether. Find the mean and root mean square deviation of the number of children who are present during the 50 days.