Questions: In a sample of 10 randomly selected women, it was found that their mean height was 63.4 inches. From previous studies, it can be assumed that the population standard deviation σ is 2.4 and that the population of height measurements is normally distributed. Construct the 95% confidence interval for the population mean.
A. (61.9,64.9)
B. (60.8,65.4)
C. (59.7,66.5)
D. (58.1,67.3)
Transcript text: In a sample of 10 randomly selected women, it was found that their mean height was 63.4 inches. From previous studies, it can be assumed that the population standard deviation $\sigma$ is 2.4 and that the population of height measurements is normally distributed. Construct the $95 \%$ confidence interval for the population mean.
A. $(61.9,64.9)$
B. $(60.8,65.4)$
C. $(59.7,66.5)$
D. $(58.1,67.3)$
Solution
Solution Steps
Step 1: Given Information
We have a sample of \( n = 10 \) randomly selected women with a mean height of \( \bar{x} = 63.4 \) inches. The population standard deviation is given as \( \sigma = 2.4 \) inches. We need to construct a \( 95\% \) confidence interval for the population mean height.
Step 2: Determine the Z-Score
For a \( 95\% \) confidence level, the significance level \( \alpha \) is \( 0.05 \). The critical value \( z \) corresponding to \( 95\% \) confidence is approximately \( 2.0 \).
Step 3: Calculate the Standard Error
The standard error (SE) of the mean is calculated using the formula:
\[
SE = \frac{\sigma}{\sqrt{n}} = \frac{2.4}{\sqrt{10}} \approx 0.758
\]
Step 4: Calculate the Margin of Error
The margin of error (ME) is given by:
\[
ME = z \cdot SE = 2.0 \cdot 0.758 \approx 1.516
\]
Step 5: Construct the Confidence Interval
The confidence interval is calculated as:
\[
\bar{x} \pm ME = 63.4 \pm 1.516
\]
This results in:
\[
(63.4 - 1.516, 63.4 + 1.516) = (61.884, 64.916)
\]
Rounding to one decimal place gives us:
\[
(61.9, 64.9)
\]
Final Answer
The \( 95\% \) confidence interval for the population mean height is \\(\boxed{(61.9, 64.9)}\\).