Sick Leave Data E34A97
1. **State the problem:**
We have a frequency distribution of the number of sick leave days per year taken by employees and need to determine if the data is discrete or continuous, find the unknown frequency $k$ given the mean, and identify the sampling technique.
2. **Part (a): Discrete or continuous data?**
The number of sick leave days is counted in whole numbers (2, 3, 4, ...), so the data is **discrete** because it consists of distinct, separate values.
3. **Part (b): Find $k$ given the mean.**
The mean number of sick leave days is given as 4.
The formula for the mean of grouped data is:
$$\text{Mean} = \frac{\sum (x_i \times f_i)}{\sum f_i}$$
where $x_i$ is the number of sick leave days and $f_i$ is the frequency (number of employees).
From the table:
\begin{align*}
\sum f_i &= 12 + 22 + 24 + 15 + k + 3 + 1 = 77 + k \\
\sum (x_i f_i) &= 2\times12 + 3\times22 + 4\times24 + 5\times15 + 6\times k + 7\times3 + 8\times1 \\
&= 24 + 66 + 96 + 75 + 6k + 21 + 8 = 290 + 6k
\end{align*}
Using the mean formula:
$$4 = \frac{290 + 6k}{77 + k}$$
Multiply both sides by $(77 + k)$:
$$4(77 + k) = 290 + 6k$$
$$308 + 4k = 290 + 6k$$
Bring terms involving $k$ to one side:
$$308 - 290 = 6k - 4k$$
$$18 = 2k$$
$$k = 9$$
4. **Part (c): Identify the sampling technique.**
Employees were arranged alphabetically and every 5th person was selected. This is an example of **systematic sampling**.
**Final answers:**
- (a) Discrete data
- (b) $k = 9$
- (c) Systematic sampling