Math Problem Statement

A normal distributed population has parameters μ = 146.7 and σ = 52.3. If a random sample of size n = 112 is selected, what is the mean and standard deviation of the distribution of sample means?

Solution

Let's solve the question based on the given information.


Given:

  • Population mean (μ\mu) = 146.7
  • Population standard deviation (σ\sigma) = 52.3
  • Sample size (nn) = 112

(a) Mean of the distribution of sample means (μxˉ\mu_{\bar{x}}):

The mean of the distribution of sample means is the same as the population mean: μxˉ=μ=146.7\mu_{\bar{x}} = \mu = 146.7


(b) Standard deviation of the distribution of sample means (σxˉ\sigma_{\bar{x}}):

The standard deviation of the sample mean (standard error) is calculated as: σxˉ=σn\sigma_{\bar{x}} = \frac{\sigma}{\sqrt{n}}

Substituting the values: σxˉ=52.3112\sigma_{\bar{x}} = \frac{52.3}{\sqrt{112}}

First, calculate 112\sqrt{112}: 11210.583\sqrt{112} \approx 10.583

Now, calculate: σxˉ=52.310.5834.94\sigma_{\bar{x}} = \frac{52.3}{10.583} \approx 4.94


Final Answers:

  • (a) μxˉ=146.7\mu_{\bar{x}} = 146.7
  • (b) σxˉ=4.94\sigma_{\bar{x}} = 4.94 (rounded to two decimal places)

Would you like a detailed breakdown of any steps?


Here are 5 related questions for further practice:

  1. What is the effect of increasing the sample size nn on σxˉ\sigma_{\bar{x}}?
  2. If the population standard deviation (σ\sigma) were smaller, how would σxˉ\sigma_{\bar{x}} change?
  3. How would the answers change if the sample size were halved?
  4. Why is the mean of the sample means equal to the population mean?
  5. What assumptions are necessary for this calculation to hold?

Tip: Larger sample sizes reduce the standard error, leading to more precise sample mean estimates.

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Math Problem Analysis

Mathematical Concepts

Normal distribution
Sampling distribution
Standard error of the mean

Formulas

μx̄ = μ
σx̄ = σ / √n

Theorems

Central Limit Theorem

Suitable Grade Level

Grades 10-12