In: Statistics and Probability
7. Use the population of {1, 3, 7}. Assume that the random samples of size n = 2 Construct a sampling distribution of the sample mean. After identifying the 9 different possible samples (with replacement), find the mean of each sample, then construct a table representing the sample the sampling distribution of the sample mean. In the table, combine values of the sample mean that are the same. (Hint: condense the table similar to examples presented in class.)
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We have the population {1,3,7}.
Let x1, x2, ..., xn be a random sample of size n.
Then the sample mean is given by the formula
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Here, since we are taking sample of size 2, say x1 and x2, the sample mean can be obtained as
case (i): Random sample of size 2 with replacement.
The following are the possible samples with their corresponding sample means.
Samples (with replacement) |
Sample means |
{1,1} | 1 |
{1,3} | 2 |
{1,7} | 4 |
{3,1} | 2 |
{3,3} | 3 |
{3,7} | 5 |
{7,1} | 4 |
{7,3} | 5 |
{7,7} | 7 |
Therefore the sampling distribution of sample mean is obtained as in the following table.
1 | 1/9 |
2 | 2/9 |
3 | 1/9 |
4 | 2/9 |
5 | 2/9 |
7 | 1/9 |
case (ii): Random sample of size 2 without replacement. (mentioned additionally, not asked in the question)
The following are the possible samples with their corresponding sample means.
Samples (without replacement) |
Sample means |
{1,3} | 2 |
{1,7} | 4 |
{3,7} | 5 |
Therefore the sampling distribution of sample mean is obtained as in the following table.
2 | 1/3 |
4 | 1/3 |
5 | 1/3 |