Refer to the Archives of Pediatrics and Adolescent Medicine (Dec. 2007) study of honey as a remedy for coughing, Exercise 2.64 (p. 62). The coughing improvement scores for the patients in the over-the-counter cough medicine dosage (DM) group, honey dosage group, and control group are reproduced in the accompanying table.

a. Find the standard deviation of the improvement scores for the honey dosage group.
b. Find the standard deviation of the improvement scores for the DM dosage group.
c. Find the standard deviation of the improvement scores for the control group.
d. Based on the results, parts a-c, which group appears to have the most variability in coughing improvement scores? The least variability?