4. A restaurant owner is concerned about the amount of time customers have to wait before being served. He collects data on the waiting times, to the nearest minute, of 20 customers. These data are listed below.
| 15, | 14, | 16, | 15, | 17, | 16, | 15, | 14, | 15, | 16, |
| 17, | 16, | 15, | 14, | 16, | 17, | 15, | 25, | 18, | 16 |
- Find the median and inter-quartile range of the waiting times.
An outlier is an observation that falls either \(1.5 \times\) (inter-quartile range) above the upper quartile or \(1.5 \times\) (inter-quartile range) below the lower quartile.
- Draw a boxplot to represent these data, clearly indicating any outliers.
- Find the mean of these data.
- Comment on the skewness of these data. Justify your answer.