3.10. A researcher in an alcoholism treatment center, to study the length of stay in the center for first-time patients, randomly selects ten records of individu- als institutionalized within the previous two years. The lengths of stay, in days, were 11, 6, 20, 9, 13, 4, 39, 13, 44, and 7.

(a) Construct a stem-and-leaf plot.

(b) Find the mean and the standard deviation, and interpret.

(e) For a similar study 25 years ago, lengths of stay for ten sampled individuals were 32, 18,