TransAir, an international airline company, has a new jumbo jet that it believes
ID: 3365786 • Letter: T
Question
TransAir, an international airline company, has a new jumbo jet that it believes will decrease the mean transatlantic flight time from Newark to London Heathrow. In order to be faster than its competitors, the mean must be less than 6 h 50 min. Because of costs, the agency monitoring the flight times only requires that eight trials be run. The results are given in the table below. If the FAA requires that the agency be 90% confident of its findings, what should the agency report? Assume that the population distribution is approximately normal.
Flight Times from Newark to London
Flight
Flying Time
Flight 1
6 hr 32 min
Flight 2
6 hr 28 min
Flight 3
6 hr 51 min
Flight 4
6 hr 2 min
Flight 5
6 hr 51 min
Flight 6
7 hr 2 min
Flight 7
6 hr 36 min
Flight 8
6 hr 42 min
Flight Times from Newark to London
Flight
Flying Time
Flight 1
6 hr 32 min
Flight 2
6 hr 28 min
Flight 3
6 hr 51 min
Flight 4
6 hr 2 min
Flight 5
6 hr 51 min
Flight 6
7 hr 2 min
Flight 7
6 hr 36 min
Flight 8
6 hr 42 min
Explanation / Answer
Mean (mu) = 398
Standard deviation = 18.385
t statistic for a 90% confidence interval in a normal distribution: t = +-1.895
lower bound: mu - t*(std.dev) = 398 - 1.895*18.385 = 363.16
upper bound: mu + t*(std.dev) = 398 + 1.895*18.385 = 432.84
These 2 statistics is what the airline needs to report. (363.16, 432.84)
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