Correct Answer - Option 3 :

\(\sqrt {\frac{{N - n}}{{N - 1}}} \)
__Explanation:__

The population correction factor is given by the formula :

\(\sqrt {\frac{{N - n}}{{N - 1}}} \)

**Sample size =** In statistics, the sample size is the measure of the number of individual samples used in an experiment for example, if we are testing 50 samples of people who watch movie in a city, then the sample size is 50.

**Sample mean = **The sample mean from a group of observations is an estimate of the population mean **(μ).**

Given a sample of size *n*, consider *n* independent random variables *X*_{1}, *X*_{2}, ..., *X*_{n}, each corresponding to one randomly selected observation. Each of these variables has the distribution of the population, with mean(μ) and standard deviation (σ).

**T****he sample mean = ****x̄ = ( Σ xi ) / n**