A company packages butter. Of 50 randomly selected packs, 8 were found to have damaged wrappers. Find an approximate \(95 \%\) confidence interval for the proportion of packs with damaged wrappers.
The mass of a pack has a normal distribution with standard deviation 8.5 g . In a random sample of 10 packs the masses, in g , are as follows.
$$\begin{array} { l l l l l l l l l l }
220 & 225 & 218 & 223 & 224 & 220 & 229 & 228 & 226 & 228
\end{array}$$
Find a 99\% confidence interval for the mean mass of a pack.