Construct a 90% confidence interval of the mean birth weight of 195 boys with sample mean = 32.7 hg, and standard deviation = 6.6 hg. O 0.777

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### Constructing a 90% Confidence Interval for Mean Birth Weight

The following exercise involves constructing a 90% confidence interval for the mean birth weight of 195 boys. The sample mean is 32.7 hg and the standard deviation is approximately 6.6 hg.

Given Data:
- **Sample Size (n)**: 195
- **Sample Mean (x̄)**: 32.7 hg
- **Standard Deviation (σ)**: 6.6 hg

### Confidence Interval Options

1. **Option A**: \( 0.777 < \text{mean} < 1 \)
2. **Option B**: \( 31.923 < \text{mean} < 33.477 \)
3. **Option C**: \( 32\% < \text{mean} < 33\% \)
4. **Option D**: \( 1.645 < \text{mean} < 1.777 \)

### Explanation of Options

- **Option A**: A very small range which is impractical given the sample mean of 32.7 hg.
- **Option B**: Provides a realistic range around the given sample mean.
- **Option C**: Represented as percentages which is not appropriate for this context.
- **Option D**: Another small range not feasible for the given sample statistics.

### Correct Configuration

To compute the correct confidence interval, use the formula for the confidence interval of the mean:

\[ \text{CI} = \bar{x} ± Z \left(\frac{\sigma}{\sqrt{n}}\right) \]

Where Z is the Z-value for the desired confidence level (for 90%, Z ≈ 1.645).

Using the given data:
\[ \text{Margin of Error} = 1.645 \left(\frac{6.6}{\sqrt{195}}\right) \approx 0.777 \]

Hence, the 90% confidence interval would be:
\[ 32.7 ± 0.777 \]

Therefore, the interval is:
\[ 31.923 < \text{mean} < 33.477 \]

**Conclusion**: The correct answer is **Option B**: \( 31.923 < \text{mean} < 33.477 \).
Transcribed Image Text:### Constructing a 90% Confidence Interval for Mean Birth Weight The following exercise involves constructing a 90% confidence interval for the mean birth weight of 195 boys. The sample mean is 32.7 hg and the standard deviation is approximately 6.6 hg. Given Data: - **Sample Size (n)**: 195 - **Sample Mean (x̄)**: 32.7 hg - **Standard Deviation (σ)**: 6.6 hg ### Confidence Interval Options 1. **Option A**: \( 0.777 < \text{mean} < 1 \) 2. **Option B**: \( 31.923 < \text{mean} < 33.477 \) 3. **Option C**: \( 32\% < \text{mean} < 33\% \) 4. **Option D**: \( 1.645 < \text{mean} < 1.777 \) ### Explanation of Options - **Option A**: A very small range which is impractical given the sample mean of 32.7 hg. - **Option B**: Provides a realistic range around the given sample mean. - **Option C**: Represented as percentages which is not appropriate for this context. - **Option D**: Another small range not feasible for the given sample statistics. ### Correct Configuration To compute the correct confidence interval, use the formula for the confidence interval of the mean: \[ \text{CI} = \bar{x} ± Z \left(\frac{\sigma}{\sqrt{n}}\right) \] Where Z is the Z-value for the desired confidence level (for 90%, Z ≈ 1.645). Using the given data: \[ \text{Margin of Error} = 1.645 \left(\frac{6.6}{\sqrt{195}}\right) \approx 0.777 \] Hence, the 90% confidence interval would be: \[ 32.7 ± 0.777 \] Therefore, the interval is: \[ 31.923 < \text{mean} < 33.477 \] **Conclusion**: The correct answer is **Option B**: \( 31.923 < \text{mean} < 33.477 \).
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