Questions: You measure 41 watermelons' weights, and find they have a mean weight of 43 ounces. Assume the population standard deviation is 11.2 ounces. Based on this, construct a 95% confidence interval for the true population mean watermelon weight.
Round your answers to two decimal places.
Transcript text: You measure 41 watermelons' weights, and find they have a mean weight of 43 ounces. Assume the population standard deviation is 11.2 ounces. Based on this, construct a $95 \%$ confidence interval for the true population mean watermelon weight.
Round your answers to two decimal places.
Solution
Solution Steps
Step 1: Given Information
We have measured the weights of 41 watermelons, resulting in a sample mean (\(\bar{x}\)) of 43 ounces. The population standard deviation (\(\sigma\)) is 11.2 ounces. We aim to construct a 95% confidence interval for the true population mean (\(\mu\)).
Step 2: Determine the Z-Score
For a 95% confidence level, the Z-score corresponding to the critical value is \(z = 1.96\).
Step 3: Calculate the Standard Error
The standard error (SE) is calculated using the formula:
\[
SE = \frac{\sigma}{\sqrt{n}} = \frac{11.2}{\sqrt{41}} \approx 1.743
\]
Step 4: Calculate the Margin of Error
The margin of error (ME) is given by:
\[
ME = z \cdot SE = 1.96 \cdot 1.743 \approx 3.42
\]
Step 5: Construct the Confidence Interval
The confidence interval is calculated as:
\[
\bar{x} \pm ME = 43 \pm 3.42
\]
This results in:
\[
(43 - 3.42, 43 + 3.42) = (39.58, 46.42)
\]
Final Answer
The 95% confidence interval for the true population mean watermelon weight is:
\[
\boxed{39.58 < \mu < 46.42}
\]