Q. "A teller at a drive-up window at a bank had the following service time (in min. ) for 20 randomly selected customers:
SAMPLE
1 2 3 4
4.5 4.6 4.5 4.7
4.2 4.5 4.6 4.6
4.2 4.4 4.4 4.8
4.3 4.7 4.4 4.5
4.3 4.3 4.6 4.9
Illustrate what would 3-sigma control limits for the process be? Illustrate what alpha risk would they provide?