The graph on p. 45 summarizes the scores obtained by 100 students on a questionnaire designed to measure managerial ability. (Scores are integer values that range from 0 to 20.A high score indicates a high level of ability.)

a. Which measurement class contains the highest proportion of test scores?

b. What proportion of the scores lie between 3.5 and 5.5?

c. What proportion of the scores are higher than 11.5?

d. How many students scored less than 5.5:'