The mean score on a 25-point placement exam in mathematics used for the past two years at a large state university is 14.3. The placement coordinator wishes to test whether the mean score on a revised version of the exam differs from 14.3. She gives the revised exam to 20 entering freshmen early in the summer; the mean score is 14.6 with standard deviation 2.4.

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### Problem Statement

The mean score on a 25-point placement exam in mathematics used for the past two years at a large state university is 14.3. The placement coordinator wishes to test whether the mean score on a revised version of the exam differs from 14.3. She gives the revised exam to 20 entering freshmen early in the summer; the mean score is 14.6 with a standard deviation of 2.4.

#### Tasks:
a. Perform the test at the 10% level of significance using the critical value approach.
b. Perform the test at the 10% level of significance using the p-value approach.

### Solution

To solve this problem, we will conduct a hypothesis test for the mean score using both the critical value approach and the p-value approach.

#### Steps to solve:

1. **State the hypotheses:**
   - Null hypothesis (H₀): µ = 14.3 (The mean score is 14.3)
   - Alternative hypothesis (H₁): µ ≠ 14.3 (The mean score is different from 14.3)

2. **Choose the significance level (α):**
   - Significance level (α) = 0.10

3. **Calculate the test statistic:**
   - We will use the t-test since the sample size (n = 20) is small.
   - The test statistic is calculated using the formula:
     \[
     t = \frac{\bar{x} - \mu_0}{s / \sqrt{n}}
     \]
     Where:
     - \(\bar{x}\) = sample mean = 14.6
     - \(\mu_0\) = population mean = 14.3
     - \(s\) = sample standard deviation = 2.4
     - \(n\) = sample size = 20

4. **Determine the critical value:**
   - For a two-tailed test at α = 0.10, the critical values for t with (n-1) degrees of freedom (df = 20 - 1 = 19) are approximately ±1.729.

5. **Decision (Critical Value Approach):**
   - If the test statistic falls outside the range of -1.729 to 1.729, we reject the null hypothesis.

6. **Decision (p-value Approach):**
   - Calculate the p-value associated
Transcribed Image Text:### Problem Statement The mean score on a 25-point placement exam in mathematics used for the past two years at a large state university is 14.3. The placement coordinator wishes to test whether the mean score on a revised version of the exam differs from 14.3. She gives the revised exam to 20 entering freshmen early in the summer; the mean score is 14.6 with a standard deviation of 2.4. #### Tasks: a. Perform the test at the 10% level of significance using the critical value approach. b. Perform the test at the 10% level of significance using the p-value approach. ### Solution To solve this problem, we will conduct a hypothesis test for the mean score using both the critical value approach and the p-value approach. #### Steps to solve: 1. **State the hypotheses:** - Null hypothesis (H₀): µ = 14.3 (The mean score is 14.3) - Alternative hypothesis (H₁): µ ≠ 14.3 (The mean score is different from 14.3) 2. **Choose the significance level (α):** - Significance level (α) = 0.10 3. **Calculate the test statistic:** - We will use the t-test since the sample size (n = 20) is small. - The test statistic is calculated using the formula: \[ t = \frac{\bar{x} - \mu_0}{s / \sqrt{n}} \] Where: - \(\bar{x}\) = sample mean = 14.6 - \(\mu_0\) = population mean = 14.3 - \(s\) = sample standard deviation = 2.4 - \(n\) = sample size = 20 4. **Determine the critical value:** - For a two-tailed test at α = 0.10, the critical values for t with (n-1) degrees of freedom (df = 20 - 1 = 19) are approximately ±1.729. 5. **Decision (Critical Value Approach):** - If the test statistic falls outside the range of -1.729 to 1.729, we reject the null hypothesis. 6. **Decision (p-value Approach):** - Calculate the p-value associated
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