Exercise 7(b) from p. 322 states:
Three groups of rats were injects, respectively, with 0.5 milligrams, 1.0 milligram, and 1.5 milligrams of a
new tranquilizer; the following are the number of minutes it took them to fall asleep:
The 0.5-milligram group: 11, 13, 9, 14, 15, 13
The 1.0-milligram group: 9, 11, 10, 8, 12
The 1.5-milligram group: 10, 5, 8, 6, 10, 9, 6