Math Problem Statement

A population of values has a normal distribution with μ = 175.7 and σ = 31.4. You intend to draw a random sample of size n = 84. What is the mean of the distribution of sample means? What is the standard deviation of the distribution of sample means (accurate to 2 decimal places)?

Solution

To solve this problem, let’s address each part step by step.

  1. Mean of the Distribution of Sample Means (μxˉ\mu_{\bar{x}}):

    • In a normal distribution, the mean of the distribution of sample means is the same as the population mean.
    • Given that the population mean (μ\mu) is 175.7, we have: μxˉ=μ=175.7\mu_{\bar{x}} = \mu = 175.7
  2. Standard Deviation of the Distribution of Sample Means (σxˉ\sigma_{\bar{x}}):

    • The standard deviation of the distribution of sample means, also known as the standard error, is given by: σxˉ=σn\sigma_{\bar{x}} = \frac{\sigma}{\sqrt{n}}
    • Here, σ=31.4\sigma = 31.4 and n=84n = 84, so: σxˉ=31.484\sigma_{\bar{x}} = \frac{31.4}{\sqrt{84}}

    Let’s calculate this:

    σxˉ=31.48431.49.1653.42\sigma_{\bar{x}} = \frac{31.4}{\sqrt{84}} \approx \frac{31.4}{9.165} \approx 3.42

So, the answers are:

  • μxˉ=175.7\mu_{\bar{x}} = 175.7
  • σxˉ3.42\sigma_{\bar{x}} \approx 3.42

Would you like further details on the calculations or concepts here?

Here are some additional questions to expand on this topic:

  1. How does sample size affect the standard deviation of the sample mean distribution?
  2. Why is the mean of the sample mean distribution the same as the population mean?
  3. How would these values change if the sample size were increased to 100?
  4. What does the Central Limit Theorem tell us about the distribution of sample means?
  5. How would the calculations change if the population were not normally distributed?

Tip: The standard deviation of the sample mean distribution decreases as the sample size increases, making larger samples more precise for estimating the population mean.

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Math Problem Analysis

Mathematical Concepts

Statistics
Normal Distribution
Sampling Distribution
Standard Error

Formulas

Mean of the sampling distribution of sample means: μ_x̄ = μ
Standard deviation of the sampling distribution of sample means: σ_x̄ = σ / √n

Theorems

Central Limit Theorem

Suitable Grade Level

Undergraduate Statistics