Use the given data to construct a confidence interval of the requested level. X = 178, N=531, Confidence level 90%

MATLAB: An Introduction with Applications
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Author:Amos Gilat
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### Constructing a Confidence Interval 

**Problem Statement:**
Use the given data to construct a confidence interval of the requested level.

**Given Data:**
- \( x = 178 \)
- \( N = 531 \)
- Confidence Level: 90%

### Instructions:
1. **Identify the Sample Proportion (\(\hat{p}\))**:
   - The sample proportion \(\hat{p}\) can be calculated using the formula \(\hat{p} = \frac{x}{N}\).
   - Here, \( x \) is the number of successes, and \( N \) is the sample size.

2. **Calculate the Sample Proportion**:
   - \(\hat{p} = \frac{178}{531}\)
   - \(\hat{p} \approx 0.3354\)

3. **Determine the Z-Score for the Confidence Level**:
   - For a 90% confidence level, the Z-score is approximately 1.645 (this value can be found in Z-tables).

4. **Calculate the Standard Error (SE)**:
   - The Standard Error (SE) is calculated using the formula \(SE = \sqrt{\frac{\hat{p}(1 - \hat{p})}{N}}\).
   - Here, \( \hat{p} \) is the sample proportion, and \( N \) is the sample size.

   \[SE = \sqrt{\frac{0.3354 \times (1 - 0.3354)}{531}} \approx 0.0205\]

5. **Calculate the Margin of Error (ME)**:
   - The Margin of Error (ME) is calculated using the formula \(ME = Z \times SE\).
   - Here, \( Z \) is the Z-score corresponding to the desired confidence level.

   \[ME = 1.645 \times 0.0205 \approx 0.0337\]

6. **Determine the Confidence Interval**:
   - The confidence interval (CI) is given by \(\hat{p} \pm ME\).

   \[
   CI = 0.3354 \pm 0.0337
   \]
   - So the interval is approximately (0.3017, 0.3691).

### Conclusion:
The 90% confidence interval for the given data is approximately (0.3017
Transcribed Image Text:### Constructing a Confidence Interval **Problem Statement:** Use the given data to construct a confidence interval of the requested level. **Given Data:** - \( x = 178 \) - \( N = 531 \) - Confidence Level: 90% ### Instructions: 1. **Identify the Sample Proportion (\(\hat{p}\))**: - The sample proportion \(\hat{p}\) can be calculated using the formula \(\hat{p} = \frac{x}{N}\). - Here, \( x \) is the number of successes, and \( N \) is the sample size. 2. **Calculate the Sample Proportion**: - \(\hat{p} = \frac{178}{531}\) - \(\hat{p} \approx 0.3354\) 3. **Determine the Z-Score for the Confidence Level**: - For a 90% confidence level, the Z-score is approximately 1.645 (this value can be found in Z-tables). 4. **Calculate the Standard Error (SE)**: - The Standard Error (SE) is calculated using the formula \(SE = \sqrt{\frac{\hat{p}(1 - \hat{p})}{N}}\). - Here, \( \hat{p} \) is the sample proportion, and \( N \) is the sample size. \[SE = \sqrt{\frac{0.3354 \times (1 - 0.3354)}{531}} \approx 0.0205\] 5. **Calculate the Margin of Error (ME)**: - The Margin of Error (ME) is calculated using the formula \(ME = Z \times SE\). - Here, \( Z \) is the Z-score corresponding to the desired confidence level. \[ME = 1.645 \times 0.0205 \approx 0.0337\] 6. **Determine the Confidence Interval**: - The confidence interval (CI) is given by \(\hat{p} \pm ME\). \[ CI = 0.3354 \pm 0.0337 \] - So the interval is approximately (0.3017, 0.3691). ### Conclusion: The 90% confidence interval for the given data is approximately (0.3017
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