Consider the population with mean 50 and standard deviation 15. We draw a sample of size 100. According to the

theorem a sampling distribution x̄ is approximately normal with mean
and standard deviation
.

1 answer

According to the Central Limit Theorem, the sampling distribution of the sample mean (\( \bar{x} \)) will be approximately normal if the sample size is sufficiently large (typically \( n \geq 30 \) is considered sufficient).

For a population with a mean (\( \mu \)) and standard deviation (\( \sigma \)), the mean and standard deviation of the sampling distribution (\( \bar{x} \)) can be described as follows:

  1. Mean of the sampling distribution (\( \mu_{\bar{x}} \)): \[ \mu_{\bar{x}} = \mu \] So, in this case, since the population mean is 50: \[ \mu_{\bar{x}} = 50 \]

  2. Standard deviation of the sampling distribution (also known as the standard error, \( \sigma_{\bar{x}} \)): \[ \sigma_{\bar{x}} = \frac{\sigma}{\sqrt{n}} \] Here, the population standard deviation is 15, and the sample size \( n \) is 100. We can calculate it as follows: \[ \sigma_{\bar{x}} = \frac{15}{\sqrt{100}} = \frac{15}{10} = 1.5 \]

Putting it all together, we have:

  • The mean of the sampling distribution \( \mu_{\bar{x}} = 50 \)
  • The standard deviation of the sampling distribution \( \sigma_{\bar{x}} = 1.5 \)

In conclusion:

  • Mean of \( \bar{x} \): \( 50 \)
  • Standard deviation of \( \bar{x} \): \( 1.5 \)