Question

Western Airlines merged with a smaller airline recently. Every day since the merger, a random sample of 30 Western flights has been analyzed. A flight that takes off more than 10 minutes after its scheduled departure time is considered to be late; otherwise, it is not late. Western’s performance over the past 10 days is shown in the table below.

               Day 1 2 3 4 5 6 7 8 9 10

# Late Flights 4 2 5 9 2 3 3 1 2 8

(I) What type of control chart would we use to monitor this process?

( Circle 1 ) (a) X-bar chart (b) R-chart (c) p-chart (d) c-chart

(II) And why? Since the sample size is given and the data is collected on regular basis (daily), therefore, p-chart must be used.

(III) What are 2-sigma control limits for this process?

(IV) Is the process in control, after you plot and analyze the Control charts? Why/Why not?

Answer 1