The difference between the actual arrival time and scheduled arrival time for 20 trips made into Dallas was noted. The flights were on the same airline at approximately the same time of day; however, half of the flights were from St. Louis (denoted as ‘‘S’’) while the other half were from New York (denoted as ‘‘N’’). Plus values indicate the number of minutes the flight was late. The times were 11.1 (S), 8.7 (S), 14.3 (N), 11.1 (S), 10.4 (N), 6.4 (N), 11.2 (S), 6.3 (N), 13.3 (S), 8.9 (N), 11.0 (S), 8.5 (N), 9.4 (S), 10.2 (N), 10.0 (N), 8.7 (S), 9.1 (S), 13.2 (N), 16.5 (N), 9.6 (S).
(a) Determine at a significance level of 0.05 whether the variability in arrival times were longer for the New York flight.
(b) Determine at a significance level of 0.05 whether on the average the arrival time from New York was longer than that from St. Louis.
(c) To save parking fees, estimate when a friend should meet the traveler at the pickup/drop-off area. Assume that the distribution of thesearrival times is representative of future flights. Consider that it takes 10 minutes to walk from the gate to the load zone and that the friend should wait only 5% of the times.