A population consisting of 5 numbers 2, 3, 6, 8, 11Consider all

samples of size ‘2’ which can be drawn with replacement from

this population. Find (i) Population mean (ii) Population

standard deviation (iii) Mean of sampling distribution of means

(iv) Standard deviation of sampling distribution of means

(v) Correction factor (vi) Standard error and verify.

Answer :

Answer:

Let's go through each part step by step for the given population and the sampling process.

**Population:**

\[ \{ 2, 3, 6, 8, 11 \} \]

**Sample size (n):** 2 (samples drawn with replacement)

**Number of elements in population (N):** 5

### (i) Population Mean

The population mean (μ) is calculated as:

\[ \mu = \frac{\sum_{i=1}^{N} x_i}{N} \]

where \( x_i \) are the elements of the population.

Calculate the population mean:

\[ \mu = \frac{2 + 3 + 6 + 8 + 11}{5} = \frac{30}{5} = 6 \]

So, the population mean is \( \mu = 6 \).

### (ii) Population Standard Deviation

The population standard deviation (σ) is calculated using:

\[ \sigma = \sqrt{\frac{\sum_{i=1}^{N} (x_i - \mu)^2}{N}} \]

Calculate deviations from the mean:

\[ (2-6)^2 = 16, \; (3-6)^2 = 9, \; (6-6)^2 = 0, \; (8-6)^2 = 4, \; (11-6)^2 = 25 \]

Sum of squared deviations:

\[ \sum (x_i - \mu)^2 = 16 + 9 + 0 + 4 + 25 = 54 \]

Population standard deviation:

\[ \sigma = \sqrt{\frac{54}{5}} \approx \sqrt{10.8} \approx 3.29 \]

So, the population standard deviation is \( \sigma \approx 3.29 \).

### (iii) Mean of Sampling Distribution of Means

The mean of the sampling distribution of means (μ_{\bar{x}}) is equal to the population mean:

\[ \mu_{\bar{x}} = \mu = 6 \]

### (iv) Standard Deviation of Sampling Distribution of Means

The standard deviation of the sampling distribution of means (standard error, SE) is calculated as:

\[ SE = \frac{\sigma}{\sqrt{n}} \]

Where \( \sigma \) is the population standard deviation and \( n \) is the sample size.

For \( n = 2 \):

\[ SE = \frac{3.29}{\sqrt{2}} \approx \frac{3.29}{1.414} \approx 2.33 \]

So, the standard deviation of the sampling distribution of means (SE) is approximately \( 2.33 \).

### (v) Correction Factor

The correction factor (also known as the finite population correction factor, FPC) is given by:

\[ \sqrt{\frac{N-n}{N-1}} \]

Where \( N \) is the population size and \( n \) is the sample size.

For \( N = 5 \) and \( n = 2 \):

\[ FPC = \sqrt{\frac{5-2}{5-1}} = \sqrt{\frac{3}{4}} = \sqrt{0.75} \approx 0.866 \]

### (vi) Standard Error and Verification

The standard error (SE) is \( SE = \frac{\sigma}{\sqrt{n}} \). We calculated \( \sigma \approx 3.29 \) and for \( n = 2 \), \( SE \approx 2.33 \).

Verification:

\[ SE = \frac{3.29}{\sqrt{2}} \approx 2.33 \]

This matches our previous calculation, confirming the standard error.

### Summary

- Population mean (μ): \( 6 \)

- Population standard deviation (σ): \( \approx 3.29 \)

- Mean of sampling distribution of means (μ_{\bar{x}}): \( 6 \)

- Standard deviation of sampling distribution of means (SE): \( \approx 2.33 \)

- Correction factor (FPC): \( \approx 0.866 \)

- Standard error (SE): \( \approx 2.33 \)

These values represent the statistical characteristics of the population and the sampling distribution based on samples of size 2 drawn with replacement from the given population.

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