Air Gascogne operates daily round-trip flights on the Toulouse–Stockholm route using a fleet of three 747s, the Eclair des Cévennes, the Eclair des Vosges and the Eclair des Alpilles. The budgeted quantity of fuel for each round-trip flight is the mean (average) fuel usage. Over the last 12 months, the average fuel usage per round-trip is 1000 litre-units with a standard deviation of 100 litre-units. A litre-unit is 1000 litres. 

Gervaise Plassans, the operations manager of Air Gascogne, uses a statistical quality control (SQC) approach in deciding whether to investigate fuel usage per round-trip flight. She investigates those flights with fuel usage greater than two standard deviations from the mean. 

In October, Plassans receives the following report for round-trip fuel usage by the three planes operating on the Toulouse–Stockholm route:

Required 

1. Using the ±2σ rule, what variance investigation decisions would be made? 

2. Present SQC charts for round-trip fuel usage for each of the three 747s in October. What inferences can you draw from them? 

Transcribed Image Text:

Eclair des Eclair des Eclair des Alpilles (litre-units) Cévennes Vosges (litre-units) Flight (litre-units) 1 1040 1030 970 2 940 940 1040 3 970 960 1110 4 1010 1070 1040 5 1050 920 1220 1070 1130 1180 7 1110 990 1260 1120 1060 1140 9. 1150 1010 1170 10 1190 930 1230