High School

The body temperatures in degrees Fahrenheit of a sample of adults in one small town are:

[tex]
\[
\begin{tabular}{|l|l|l|l|l|l|l|l|l|l|l|l|}
\hline
97.7 & 99.3 & 96.4 & 99.9 & 98.2 & 98.1 & 96.5 & 98.8 & 97.5 & 96.8 & 99.5 & 98.4 \\
\hline
\end{tabular}
\]
[/tex]

Assume body temperatures of adults are normally distributed. Based on this data, find the [tex]$95\%$[/tex] confidence interval of the mean body temperature of adults in the town. Enter your answer as an open interval (i.e., parentheses) accurate to 3 decimal places.

Assume the data is from a normally distributed population.

[tex]\[ \text{95\% C.I.} = (97.434, 98.750) \][/tex]

Answer :

To find the 95% confidence interval for the mean body temperature of adults in the town based on the given data, follow these steps:

1. Collect the Data: The body temperatures provided are:
- [tex]\( 97.7, 99.3, 96.4, 99.9, 98.2, 98.1, 96.5, 98.8, 97.5, 96.8, 99.5, 98.4 \)[/tex]

2. Calculate the Sample Mean:
- Add all the temperatures together and divide by the number of data points (12 in this case).
- The sample mean is calculated as approximately [tex]\( 98.092 \)[/tex].

3. Calculate the Sample Standard Deviation:
- Use the formula for the sample standard deviation, which accounts for a degree of freedom (n-1 where n is the sample size).
- The sample standard deviation is approximately [tex]\( 1.163 \)[/tex].

4. Determine the Sample Size (n):
- There are 12 data points in the sample, so [tex]\( n = 12 \)[/tex].

5. Find the t-score for the 95% Confidence Level:
- With a confidence level of 95% and 11 degrees of freedom (n-1), find the t-score using a t-distribution table.
- The t-score is approximately [tex]\( 2.201 \)[/tex].

6. Calculate the Margin of Error:
- The margin of error is calculated using the formula:
[tex]\[
\text{Margin of Error} = t \times \left(\frac{\text{Sample Standard Deviation}}{\sqrt{n}}\right)
\][/tex]
- Substituting the values, the margin of error is approximately [tex]\( 0.739 \)[/tex].

7. Determine the Confidence Interval:
- Calculate the lower bound by subtracting the margin of error from the sample mean.
- Calculate the upper bound by adding the margin of error to the sample mean.
- The 95% confidence interval is approximately [tex]\((97.352, 98.831)\)[/tex].

Therefore, the 95% confidence interval for the mean body temperature of adults in this town is [tex]\((97.352, 98.831)\)[/tex] when rounded to three decimal places.