(Prepared by Flight Operations)

Sample Number	Delayed Flights	Sample Number	Delayed Flights	Sample Number	Delayed Flights
1	1	11	5	21	2
2	2	12	4	22	2
3	7	13	7	23	1
4	2	14	3	24	0
5	0	15	0	25	6
6	1	16	1	26	4
7	0	17	2	27	2
8	1	18	0	28	1
9	1	19	1	29	1
10	4	20	3	30	0

Notes:

• A random sample of 50 flights was taken over a 30 day period.
• A flight more than 20 minutes late is classified as a delayed flight.
• The airline industrys lower and upper (3-sigma) control limits for delayed flights are 2% to 15%.
• The average of delayed flights for the industry is 8%.

It is important to note that in real life situation, a significant amount of effort is required in collecting the data by examining various documents and interviewing different people, developing assumptions to simplify the analysis, and presenting the data in an understandable form.