College

If a sample of 66 employees is taken from a population of 820 employees, the sample variance, [tex]$s^2$[/tex], is the variance of how many employees' salaries?

A. 66
B. 820
C. Neither 66 nor 820
D. Both 66 and 820

Answer :

To determine the number of employees whose salaries are represented by the sample variance [tex]\( s^2 \)[/tex], let's break down the concepts:

1. Population and Sample:
- A population is the entire group that you are interested in studying. In this case, it's the 820 employees.
- A sample is a smaller group selected from the population for the purpose of statistical analysis. Here, a sample of 66 employees is taken.

2. Sample Variance ([tex]\( s^2 \)[/tex]):
- The sample variance is a measure of how much the salaries within the sample (66 employees) vary. It specifically describes the variability within this group.
- It is calculated using only the data from the sample, not the entire population. This provides an estimate of the variance of the sample itself.

3. Answer:
- Since the sample variance [tex]\( s^2 \)[/tex] is calculated based on the subset of 66 employees, it represents the variance of those 66 employees' salaries.

Therefore, the number of employees' salaries represented by the sample variance [tex]\( s^2 \)[/tex] is 66. Thus, the correct answer is:
- A. 66