If n=19, a(x-bar)=31, and s=9, find the margin of error at a 80% confidence level Give your answer to two decimal places.

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### Finding the Margin of Error at an 80% Confidence Level

Given the following sample data:

- Sample size (n) = 19
- Sample mean (x̄) = 31
- Sample standard deviation (s) = 9

You are required to find the margin of error at an 80% confidence level. Please provide your answer to two decimal places.

### Calculation Steps

1. **Determine the critical value (t*)**:
   - For an 80% confidence level and a sample size of 19, you need to find the degrees of freedom (df), which is n - 1. Therefore, df = 19 - 1 = 18.
   - You can look up the critical value (t*) for an 80% confidence level and 18 degrees of freedom using a t-distribution table or calculator.

2. **Calculate the standard error (SE)**:
   - SE = s / √n
   - Substitute the given values: SE = 9 / √19

3. **Calculate the Margin of Error (ME)**:
   - ME = t* × SE
   - Use the critical value obtained from the t-distribution table and the standard error calculated in the previous step.

Once you calculate the above values, you'll have the margin of error rounded to two decimal places.

#### Graphical Explanation

(Since no graph or diagram is provided in the image, here is an explanation you could provide if relevant):

A t-distribution graph can help visualize the concept. For an 80% confidence level, the middle 80% of the t-distribution curve is shaded, leaving 10% in each of the two tails. The critical value (t*) is where the tails begin, and it defines the cutoff values for the sample data.

### Answer

Enter your calculated margin of error in the provided answer box below.

(If you are an instructor, consider providing interactive tools or links to t-distribution tables and calculators to facilitate learning.)
Transcribed Image Text:### Finding the Margin of Error at an 80% Confidence Level Given the following sample data: - Sample size (n) = 19 - Sample mean (x̄) = 31 - Sample standard deviation (s) = 9 You are required to find the margin of error at an 80% confidence level. Please provide your answer to two decimal places. ### Calculation Steps 1. **Determine the critical value (t*)**: - For an 80% confidence level and a sample size of 19, you need to find the degrees of freedom (df), which is n - 1. Therefore, df = 19 - 1 = 18. - You can look up the critical value (t*) for an 80% confidence level and 18 degrees of freedom using a t-distribution table or calculator. 2. **Calculate the standard error (SE)**: - SE = s / √n - Substitute the given values: SE = 9 / √19 3. **Calculate the Margin of Error (ME)**: - ME = t* × SE - Use the critical value obtained from the t-distribution table and the standard error calculated in the previous step. Once you calculate the above values, you'll have the margin of error rounded to two decimal places. #### Graphical Explanation (Since no graph or diagram is provided in the image, here is an explanation you could provide if relevant): A t-distribution graph can help visualize the concept. For an 80% confidence level, the middle 80% of the t-distribution curve is shaded, leaving 10% in each of the two tails. The critical value (t*) is where the tails begin, and it defines the cutoff values for the sample data. ### Answer Enter your calculated margin of error in the provided answer box below. (If you are an instructor, consider providing interactive tools or links to t-distribution tables and calculators to facilitate learning.)
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