Central Airlines would like to set up a control chart to monitor its on-time arrival performance. Each day over a 10-day period Central Airlines chose 30 flights at random and tracked the number of late arrivals in each sample. The results are as follows:
|
DAY
|
SAMPLE SIZE
|
NO. OF LATE- ARRIVING FLIGHTS
|
|
1
|
30
|
2
|
|
2
|
30
|
3
|
|
3
|
30
|
4
|
|
4
|
30
|
0
|
|
5
|
30
|
1
|
|
6
|
30
|
6
|
|
7
|
30
|
4
|
|
8
|
30
|
2
|
|
9
|
30
|
3
|
|
10
|
30
|
5
|
a. Calculate p.
b. Set up a p chart to track the proportion of late arrivals. (Note: Each sample consists of 30 observations.)
c. Airline travel is characterized by busy and slow seasons. As a result, what is "normal" during one time of the year wouldn't be "normal" at some other time. What difficulties might arise as a result of using a single control chart to track the proportion of late arrivals? What could Central Airlines do about this?