Based on a national sample of 549 teenagers, 203 expressed a desire for more discussions about school. With a 99% confidence level, the estimated proportion of all teenagers wanting more school discussions is between 33.5% and 40.2%.
To estimate the proportion of all teenagers who want more discussions about school, we can use the formula for calculating the confidence interval for a proportion. The formula is given by:
![\[ \text{Confidence Interval} = \hat{p} \pm Z * \sqrt{\frac{\hat{p}(1 - \hat{p})}{n}} \]](https://img.qammunity.org/2024/formulas/mathematics/high-school/sn6a22i6ihdhky1khpnjrid2dcpg69py8p.png)
Where:
-
is the sample proportion,
- Z is the Z-score corresponding to the desired confidence level,
- n is the sample size.
In this case, the sample proportion
is the proportion of teenagers who want to talk about school, which is 203/549. The Z-score for a 99% confidence level is approximately 2.576. The sample size n is 549.
Let's plug these values into the formula:
![\[ \text{Confidence Interval} = (203)/(549) \pm 2.576 * \sqrt{((203)/(549) * \left(1 - (203)/(549)\right))/(549)} \]](https://img.qammunity.org/2024/formulas/mathematics/high-school/gk5krrumi37wf3aocclb42uv0ve5rzds9n.png)
Now, calculate the values:
![\[ \text{Confidence Interval} = 0.369 \pm 2.576 * \sqrt{(0.369 * 0.631)/(549)} \]](https://img.qammunity.org/2024/formulas/mathematics/high-school/6ad93qsadc821qnuo60xy2wmmfm7zuklx9.png)
Calculate the standard error:
![\[ \text{Standard Error} = \sqrt{(0.369 * 0.631)/(549)} \]\[ \text{Standard Error} \approx 0.026 \]](https://img.qammunity.org/2024/formulas/mathematics/high-school/wzfc3r651bm4u8i0esynx6a34croqnw25f.png)
Now, substitute the standard error into the confidence interval formula:
![\[ \text{Confidence Interval} = 0.369 \pm 2.576 * 0.026 \]](https://img.qammunity.org/2024/formulas/mathematics/high-school/f3o7l6khkr9yc58t4hj9vgnhk7m9ph3zfb.png)
Now, calculate the upper and lower bounds of the confidence interval:
![\[ \text{Lower Bound} = 0.369 - (2.576 * 0.026) \]\[ \text{Upper Bound} = 0.369 + (2.576 * 0.026) \]](https://img.qammunity.org/2024/formulas/mathematics/high-school/6z6uini2txj9q5064gflm8fkt1xcayhd7b.png)
With a 99% confidence level, the estimated proportion of all teenagers wanting more school discussions is between 33.5% and 40.2%. This gives you the 99% confidence interval for the proportion of teenagers who want more discussions about school.
Keep in mind that the confidence interval is an estimate, and it indicates a range within which we are reasonably confident the true proportion lies. In this case, it represents the proportion of all teenagers who want more discussions about school.