Eight Instances of a Worker Doing a Task Were Observed

Short Answer

Eight instances of a worker doing a task were observed as follows: $$\begin{array} { l r r r r r r r r } \text { Observation } & 1 & 2 & 3 & 4 & 5 & 6 & 7 & 8 \\\hline \text { Time (seconds) } & 17 & 18 & 15 & 14 & 13 & 15 & 16 & 12\end{array}$$ How many observations would be needed to be 99.74 percent confident that the maximum error is 5 percent of the observed time? Assume that the standard deviation of the task time is two seconds.