A population has a mean of 100 and a standard deviation of 15. For samples of size 25, find the mean and standard error of the sampling distribution of the sample mean.
Solution
Problem
A population has a mean of 100 and a standard deviation of 15. For samples of size 25, find the mean and standard error of the sampling distribution of the sample mean.
Step 1: Find the mean of the sampling distribution.
The mean of the sampling distribution of the sample mean equals the population mean.
Therefore:
μ_x̄ = μ = 100
Step 2: Recall the standard error formula.
The standard error of the sample mean is:
SE = σ / √n
Step 3: Identify the values.
σ = 15
n = 25
Step 4: Substitute into the formula.
SE = 15 / √25
Step 5: Simplify.
√25 = 5
SE = 15 / 5
SE = 3
Therefore, the sampling distribution has a mean of 100 and a standard error of 3.
Result
Mean = 100; Standard error = 3