[填空题]
At the end of a working day, a su6igbz 9: wdhd j6fis-3ga5 +ybrvey was conducted at a company hea8pdois4/5qs ;mm(ut jd office asking employees howu mjsi/ m;t(so45d q8p frequently they take sick leave days per year.
The data is shown in the following table.
1. State whether the data is discrete or continuous.
The mean number of sick leave days per year is 4 .
2. Find the value of k .
In this survey, these employees were arranged in alphabetical order and every 5th person was asked for the number of sick leaves per year.
3. Identify the sampling technique used in the survey.
