Math Problem Statement

Use the Central Limit Theorem to find the mean and standard error of the mean of the indicated sampling distribution. The amounts of time employees of a telecommunications company have worked for the company are normally distributed with a mean of 5.1 years and a standard deviation of 1.8 years. Random samples of size 20 are drawn from the population and the mean of each sample is determined.

Solution

We are tasked with using the Central Limit Theorem (CLT) to find the mean and the standard error of the mean for the sampling distribution.

Given Information:

  • Population mean (μ\mu) = 5.1 years
  • Population standard deviation (σ\sigma) = 1.8 years
  • Sample size (nn) = 20

1. Mean of the Sampling Distribution

According to the Central Limit Theorem, the mean of the sampling distribution of the sample mean is equal to the population mean:
μxˉ=μ\mu_{\bar{x}} = \mu Thus:
μxˉ=5.1 years\mu_{\bar{x}} = 5.1 \ \text{years}


2. Standard Error of the Mean (SE)

The standard error of the mean is calculated using the formula:
SE=σn\text{SE} = \frac{\sigma}{\sqrt{n}} Substitute the values:
SE=1.820\text{SE} = \frac{1.8}{\sqrt{20}}

First, calculate 20\sqrt{20}:
204.47\sqrt{20} \approx 4.47

Now compute SE:
SE=1.84.470.403\text{SE} = \frac{1.8}{4.47} \approx 0.403


Final Answers:

  1. Mean of the sampling distribution: 5.1 years5.1 \ \text{years}
  2. Standard error of the mean: 0.403 years0.403 \ \text{years}

Would you like a further breakdown or explanation of any step?


Related Questions:

  1. What happens to the standard error if the sample size increases to 50?
  2. How does the Central Limit Theorem apply when the population is not normally distributed?
  3. What is the probability that a sample mean falls within 1 standard error of the population mean?
  4. How would you interpret the standard error in practical terms?
  5. What changes occur in the sampling distribution if the population standard deviation doubles?

Tip: As the sample size increases, the standard error decreases, making the sample means more precise estimates of the population mean.

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Math Problem Analysis

Mathematical Concepts

Central Limit Theorem
Sampling Distributions
Standard Error of the Mean

Formulas

Mean of Sampling Distribution: μx̄ = μ
Standard Error: SE = σ / √n

Theorems

Central Limit Theorem

Suitable Grade Level

Grades 11-12, College Level