One aspect of a study of gender differences involves the play behavior of monkeys during the first year of life (courtesy of H. Harlow, U. W. Primate Laboratory). Six male and six female monkeys are observed in groups of four families during several ten-minute test sessions. The mean tot al number of times each monkey initiates play with another age mate is recorded.

(a) Plot the observations.
(b) Test for equality using the Wilcoxon rank-sum test with a approximately .05.
(c) Determine the significance probability.

Males 3.64 3.11 3.80 3.58 4.55 Females 1.91 2.06 1.78 3.92 2.00 1.30 2.32