In a random sample of 24 people, the mean commute time to work was 31.2 minutes and the standard deviation was 7.1 minutes. Assume the population is normally distributed and use a t-distribution to construct a 80% confidence interval for the population mean μ. What is the margin of error of µ? Interpret the results. The confidence interval for the population mean u is (Round to one decimal place as needed.) The margin of error of μ is. (Round to one decimal place as needed.) Interpret the results. OA. If a large sample of people are taken approximately 80% of them will have commute times between the bounds of the confidence interval. OB. With 80% confidence, it can be said that the commute time is between the bounds of the confidence interval. OC. It can be said that 80% of people have a commute time between the bounds of the confidence interval. O D. With 80% confidence, it can be said that the population mean commute time is between the bounds of the confidence interval.

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**Sample Problem Statement:**

In a random sample of 24 people, the mean commute time to work was 31.2 minutes and the standard deviation was 7.1 minutes. Assume the population is normally distributed and use a t-distribution to construct an 80% confidence interval for the population mean μ. What is the margin of error of μ? Interpret the results.

---

**Solution:**

**1. Construct the Confidence Interval:**

The confidence interval for the population mean μ is ( ___ , ___ ).
(Round to one decimal place as needed).

**2. Calculate the Margin of Error:**

The margin of error of μ is ___.
(Round to one decimal place as needed).

---

**Interpretation of Results:**

Select the correct interpretation:

A. O If a large sample of people are taken approximately 80% of them will have commute times between the bounds of the confidence interval.
B. O With 80% confidence, it can be said that the commute time is between the bounds of the confidence interval.
C. O It can be said that 80% of people have a commute time between the bounds of the confidence interval.
D. O With 80% confidence, it can be said that the population mean commute time is between the bounds of the confidence interval.

---

**Explanation:**

To solve this problem, follow these steps:

1. **Identify the sample statistics:** 
   - Mean (\(\bar{x}\)) = 31.2 minutes
   - Standard deviation (s) = 7.1 minutes
   - Sample size (n) = 24

2. **Determine the t-score for the 80% confidence level:** 
   - Degrees of freedom (df) = n - 1 = 24 - 1 = 23
   - Use a t-distribution table or calculator to find the t-score for 80% confidence with 23 degrees of freedom.

3. **Calculate the Margin of Error (E):**
   \[
   E = t \times \left(\frac{s}{\sqrt{n}}\right)
   \]

4. **Construct the Confidence Interval:**
   \[
   \text{CI} = \bar{x} \pm E
   \]

Remember to round the final answers to one decimal place as instructed.
Transcribed Image Text:**Sample Problem Statement:** In a random sample of 24 people, the mean commute time to work was 31.2 minutes and the standard deviation was 7.1 minutes. Assume the population is normally distributed and use a t-distribution to construct an 80% confidence interval for the population mean μ. What is the margin of error of μ? Interpret the results. --- **Solution:** **1. Construct the Confidence Interval:** The confidence interval for the population mean μ is ( ___ , ___ ). (Round to one decimal place as needed). **2. Calculate the Margin of Error:** The margin of error of μ is ___. (Round to one decimal place as needed). --- **Interpretation of Results:** Select the correct interpretation: A. O If a large sample of people are taken approximately 80% of them will have commute times between the bounds of the confidence interval. B. O With 80% confidence, it can be said that the commute time is between the bounds of the confidence interval. C. O It can be said that 80% of people have a commute time between the bounds of the confidence interval. D. O With 80% confidence, it can be said that the population mean commute time is between the bounds of the confidence interval. --- **Explanation:** To solve this problem, follow these steps: 1. **Identify the sample statistics:** - Mean (\(\bar{x}\)) = 31.2 minutes - Standard deviation (s) = 7.1 minutes - Sample size (n) = 24 2. **Determine the t-score for the 80% confidence level:** - Degrees of freedom (df) = n - 1 = 24 - 1 = 23 - Use a t-distribution table or calculator to find the t-score for 80% confidence with 23 degrees of freedom. 3. **Calculate the Margin of Error (E):** \[ E = t \times \left(\frac{s}{\sqrt{n}}\right) \] 4. **Construct the Confidence Interval:** \[ \text{CI} = \bar{x} \pm E \] Remember to round the final answers to one decimal place as instructed.
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