Question

The average number of hours of flying time for pilots at American Airlines is 49 hours per month. This value was determined from a survey of 100 pilots. The sample standard deviation was 8.5 hours.

- Develop a 95% confidence interval for the average number of flying hours per month.

- Suppose the average flying time per month for United Airlines pilots was 46 hours per month. What specifically can you say about the difference in flying time between the airlines?

Answer #1

a)

sample mean 'x̄= | 49.000 |

sample size n= | 100.00 |

sample std deviation s= | 8.500 |

std error 'sx=s/√n=8.5/√100 = | 0.8500 |

for 95% CI; and 99 df, value of t= | 1.984 | |

margin of error E=t*std error = | 1.686 | |

lower bound=sample mean-E = | 47.314 | |

Upper bound=sample mean+E = | 50.686 | |

from above
95% confidence interval for population mean
=(47.31,50.69) |

b)

since average flying time for United Airlines pilots is less than interval values of above confidence interval

we can conclude with 95% confidence that average flying time for pilots at American Airlines is greater than the average flying time per month for United Airlines pilots

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