1. Samples of n= 36 scores are selected from a population. If the distribution of sample means has an expected value of µM= 30 and a standard error of ơM= 4, what is the mean and the standard deviation for the population?

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### Understanding Sampling Distributions

1. **Problem 1: Determining Population Parameters**
   - _Scenario_: Samples of \( n = 36 \) scores are selected from a population. The distribution of sample means has an expected value \( \mu_M = 30 \) and a standard error \( \sigma_M = 4 \).
   - _Question_: What are the mean and the standard deviation for the population?

   **Solution**: 
   - The standard error of the mean is given by \( \sigma_M = \frac{\sigma}{\sqrt{n}} \).
   - Substituting the values: \( 4 = \frac{\sigma}{\sqrt{36}} \).
   - Solving for \( \sigma \), we get \( \sigma = 4 \times 6 = 24 \).
   - Therefore, the population mean \( \mu = \mu_M = 30 \) and the population standard deviation \( \sigma = 24 \).

---

2. **Problem 2: Expected Value for Sample Mean**
   - _Scenario_: A sample of \( n = 4 \) scores with \( M = 43 \) is selected from a normal population with \( \mu = 40 \) and \( \sigma = 8 \).
   - _Question_: What is the expected value for the sample mean?

   **Solution**:
   - The expected value of the sample mean \( \mu_M \) is equal to the population mean \( \mu \).
   - Therefore, the expected value for the sample mean is \( \mu_M = 40 \).

---

3. **Problem 3: Conditions for Normality of Sample Means Distribution**
   - _Question_: Under which circumstance will the distribution of sample means be normal?
     - a. It is always normal
     - b. Only if the population distribution is normal
     - c. Only if the sample size is greater than 30
     - d. If the population is normal or if the sample size is greater than 30

   **Solution**:
   - The Central Limit Theorem states that the distribution of sample means will be approximately normal if the sample size is sufficiently large (usually \( n > 30 \)), or if the population from which samples are drawn is normal.
   - Therefore, the correct choice is: **d. If the population is normal or if the sample size is greater than
Transcribed Image Text:### Understanding Sampling Distributions 1. **Problem 1: Determining Population Parameters** - _Scenario_: Samples of \( n = 36 \) scores are selected from a population. The distribution of sample means has an expected value \( \mu_M = 30 \) and a standard error \( \sigma_M = 4 \). - _Question_: What are the mean and the standard deviation for the population? **Solution**: - The standard error of the mean is given by \( \sigma_M = \frac{\sigma}{\sqrt{n}} \). - Substituting the values: \( 4 = \frac{\sigma}{\sqrt{36}} \). - Solving for \( \sigma \), we get \( \sigma = 4 \times 6 = 24 \). - Therefore, the population mean \( \mu = \mu_M = 30 \) and the population standard deviation \( \sigma = 24 \). --- 2. **Problem 2: Expected Value for Sample Mean** - _Scenario_: A sample of \( n = 4 \) scores with \( M = 43 \) is selected from a normal population with \( \mu = 40 \) and \( \sigma = 8 \). - _Question_: What is the expected value for the sample mean? **Solution**: - The expected value of the sample mean \( \mu_M \) is equal to the population mean \( \mu \). - Therefore, the expected value for the sample mean is \( \mu_M = 40 \). --- 3. **Problem 3: Conditions for Normality of Sample Means Distribution** - _Question_: Under which circumstance will the distribution of sample means be normal? - a. It is always normal - b. Only if the population distribution is normal - c. Only if the sample size is greater than 30 - d. If the population is normal or if the sample size is greater than 30 **Solution**: - The Central Limit Theorem states that the distribution of sample means will be approximately normal if the sample size is sufficiently large (usually \( n > 30 \)), or if the population from which samples are drawn is normal. - Therefore, the correct choice is: **d. If the population is normal or if the sample size is greater than
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