A dancing class has 40 students. The following is the attendance record for 12 lessons.

Observation	1	2	3	4	5	6	7	8	9	10	11	12
No. of absent students	0	5	3	2	3	5	1	0	2	4	3	7

You are required to answer the following questions:

1. [3 marks] What type of control chart (mean chart, range chart, p-chart, or c-chart) should be used to monitor this process? Why?

2. [6 marks] Suppose the mean absence rate in each lesson is known and equals 9:8%. Is the process in control or out of control with 1-sigma, 2-sigma, and 3-sigma control limits, respectively? You should provide justications. [Note: You dont need to plot the control charts to draw the conclusion.]

3. [6 marks] Suppose the mean absence rate in each lesson is unknown. Is the process in control or out of control with 1-sigma, 2-sigma, and 3-sigma control limits, respectively? You should provide justications. [Note: You dont need to plot the control charts to draw the conclusion.]