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.

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

2. 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