8. In a random sample of 400 voters, 208 support the new bonding bill. Find the 98% confidence interval for the true proportion of voters who support the bill. Interpret the interval.

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**Exercise: Confidence Interval Calculation for Voter Support**

In a random sample of 400 voters, 208 support the new bonding bill. Find the 98% confidence interval for the true proportion of voters who support the bill. Interpret the interval.

**Explanation:**

To solve this problem, we'll calculate the confidence interval for the proportion of voters who support the bill using the following steps:

1. **Calculate the sample proportion (p̂):**
   \[
   p̂ = \frac{208}{400} = 0.52
   \]

2. **Choose the confidence level:**
   The confidence level is 98%, which means we are looking for a z-score associated with this confidence level. For a 98% confidence level, the z-score is approximately 2.33.

3. **Calculate the standard error (SE) for the proportion:**
   \[
   SE = \sqrt{\frac{p̂(1 - p̂)}{n}} = \sqrt{\frac{0.52 \times 0.48}{400}} \approx 0.02487
   \]

4. **Calculate the margin of error (ME):**
   \[
   ME = z \times SE = 2.33 \times 0.02487 \approx 0.05794
   \]

5. **Determine the confidence interval:**
   \[
   \text{Confidence interval} = p̂ \pm ME = 0.52 \pm 0.05794
   \]
   \[
   \text{Lower bound} = 0.46206
   \]
   \[
   \text{Upper bound} = 0.57794
   \]

**Interpretation:**

We are 98% confident that the true proportion of voters who support the new bonding bill is between 46.2% and 57.8%.

**Visual Representation:**

The small diagram on the right is a bell curve, representing the normal distribution. The shaded region under the curve corresponds to the 98% confidence level, showing the range in which the true proportion is likely to fall.
Transcribed Image Text:**Exercise: Confidence Interval Calculation for Voter Support** In a random sample of 400 voters, 208 support the new bonding bill. Find the 98% confidence interval for the true proportion of voters who support the bill. Interpret the interval. **Explanation:** To solve this problem, we'll calculate the confidence interval for the proportion of voters who support the bill using the following steps: 1. **Calculate the sample proportion (p̂):** \[ p̂ = \frac{208}{400} = 0.52 \] 2. **Choose the confidence level:** The confidence level is 98%, which means we are looking for a z-score associated with this confidence level. For a 98% confidence level, the z-score is approximately 2.33. 3. **Calculate the standard error (SE) for the proportion:** \[ SE = \sqrt{\frac{p̂(1 - p̂)}{n}} = \sqrt{\frac{0.52 \times 0.48}{400}} \approx 0.02487 \] 4. **Calculate the margin of error (ME):** \[ ME = z \times SE = 2.33 \times 0.02487 \approx 0.05794 \] 5. **Determine the confidence interval:** \[ \text{Confidence interval} = p̂ \pm ME = 0.52 \pm 0.05794 \] \[ \text{Lower bound} = 0.46206 \] \[ \text{Upper bound} = 0.57794 \] **Interpretation:** We are 98% confident that the true proportion of voters who support the new bonding bill is between 46.2% and 57.8%. **Visual Representation:** The small diagram on the right is a bell curve, representing the normal distribution. The shaded region under the curve corresponds to the 98% confidence level, showing the range in which the true proportion is likely to fall.
Expert Solution
Step 1

Here For 98 Percent confidence Interval

From Z NORMAL TABLE 

Zc=2.33

And Here given For Support for New Bonding Bill

Sample Size =400=n

No people support New Bonding Bill =X=208

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