Use the Frequency Distribution to Find the Mean

$\begin{array}{|lc|}\hline \text { Shipment time (hours) } & \text { Frequency t} \\\hline 22.5-27.5 & 23 \\27.5-32.5 & 401 \\32.5-37.5 & 794 \\37.5-42.5 & 703 \\42.5-47.5 & 503 \\47.5-52.5 & 41\\\hline\end{array}$ Use the frequency distribution to find the mean. Please round your answer to the nearest integer, if necessary.
Use the frequency distribution to find the sample standard deviation. Please round your answer to the nearest integer, if necessary.
Does the data form a normal distribution? Remember: if the data fall within 2% of the empirical rule of 68%, 95%, and 99.7% for one, two, or three standard deviations, respectively, they form a normal distribution.