A State university is interested in monitoring and controlling the number of students dropping every semester. The average academic drop in every semester is expected to be around 4 percent. Information about the last 4 semesters is as follows:

Sample # Sample size Number of Drops

1 200 12

2 120 12

3 200 10

4 150 14

Set up appropriate 3-standard deviation control limits for the problem.

Are samples 1-4 under control? Explain.