An article reported that for a sample of 45 kitchens with gas cooking appliances monitored during a one-week period, the sample mean Co, level (ppm) was 654.16, and the sample standard deviation was 165.23. (a) Calculate and interpret a 95% (two-sided) confidence interval for true average co, level in the population of all homes from which the sample was selected. (Round your answers to two decimal places.) ) ppm Interpret the resulting interval. O we are 95% confident that the true population mean lies below this interval. O we are 95% confident that this interval does not contain the true population mean. O we are 95% confident that the true population mean lies above this interval. O we are 95% confident that this interval contains the true population mean. (b) Suppose the investigators had made a rough guess of 177 for the value of s before collecting data. What sample size would be necessary to obtain an interval width of 52 ppm for a confidence level of 95%? (Round your answer up to the nearest whole number.) kitchens

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Please solve the screenshot, thanks!! The answers are not (604.52, 703.80) for (a) nor 45 for (b). 

### Understanding Confidence Intervals in Real-World Measurements

An article reported data from a study on gas cooking appliances in 45 different kitchens. In this study, the carbon dioxide (CO2) levels were monitored over one week. Here, we'll walk through calculating and interpreting a 95% confidence interval for the true average CO2 level in the population.

#### Study Details:

- **Sample size (n):** 45 kitchens
- **Sample Mean CO2 level:** 654.16 ppm
- **Sample Standard Deviation (s):** 165.23 ppm

### Step-by-Step Calculation:

#### (a) Calculate and interpret a 95% confidence interval for the true average CO2 level:

- **Formula Used:** The confidence interval can be calculated using the formula:
  
  \[ \bar{x} \pm t^* \left(\frac{s}{\sqrt{n}}\right) \]

  Where:
  - \( \bar{x} \) = sample mean
  - \( t^* \) = t-multiplier from the t-distribution for 95% confidence
  - \( s \) = sample standard deviation
  - \( n \) = sample size

- **Determine the Interval:**
   - Enter values in the provided fields as calculated.
   - Round answers to two decimal places.

##### **Interpretation:**

- Select the statement: "We are 95% confident that this interval contains the true population mean."
- This means if we were to take many samples and create intervals, 95% would contain the true population mean.

#### (b) Considering Sample Size:

- **Scenario:** If investigators guessed \( s = 177 \) before data collection,
- **Goal:** Determine sample size for an interval width of 52 ppm at 95% confidence.

- **Calculation Tip:** Use the formula involving desired width to find the necessary sample size.

**Input:** 
- Fill in the box with the calculated number of kitchens needed.

This educational exercise exemplifies how statistical methods can help us estimate averages and make informed decisions based on data.
Transcribed Image Text:### Understanding Confidence Intervals in Real-World Measurements An article reported data from a study on gas cooking appliances in 45 different kitchens. In this study, the carbon dioxide (CO2) levels were monitored over one week. Here, we'll walk through calculating and interpreting a 95% confidence interval for the true average CO2 level in the population. #### Study Details: - **Sample size (n):** 45 kitchens - **Sample Mean CO2 level:** 654.16 ppm - **Sample Standard Deviation (s):** 165.23 ppm ### Step-by-Step Calculation: #### (a) Calculate and interpret a 95% confidence interval for the true average CO2 level: - **Formula Used:** The confidence interval can be calculated using the formula: \[ \bar{x} \pm t^* \left(\frac{s}{\sqrt{n}}\right) \] Where: - \( \bar{x} \) = sample mean - \( t^* \) = t-multiplier from the t-distribution for 95% confidence - \( s \) = sample standard deviation - \( n \) = sample size - **Determine the Interval:** - Enter values in the provided fields as calculated. - Round answers to two decimal places. ##### **Interpretation:** - Select the statement: "We are 95% confident that this interval contains the true population mean." - This means if we were to take many samples and create intervals, 95% would contain the true population mean. #### (b) Considering Sample Size: - **Scenario:** If investigators guessed \( s = 177 \) before data collection, - **Goal:** Determine sample size for an interval width of 52 ppm at 95% confidence. - **Calculation Tip:** Use the formula involving desired width to find the necessary sample size. **Input:** - Fill in the box with the calculated number of kitchens needed. This educational exercise exemplifies how statistical methods can help us estimate averages and make informed decisions based on data.
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