Answer
$205.2\lt\mu\lt230.2$
Work Step by Step
1. Based on the data set we can find $\bar X=217.7, s=17.49 , n=10 $
2. At the 95% confidence and $df=9$, the critical t-value is
$t_{\alpha/2}=2.262$ (use table F)
3. The margin of error can be
found as $E=2.262\times\frac{17.49}{\sqrt {10}}=12.5$
4. Thus, the interval of the true mean can be estimated as
$\bar X-E\lt\mu\lt\bar X+E$ which gives $205.2\lt\mu\lt230.2$
