Question

A random sample of 25 roundtrip flights between Philadelphia and Dallas has an average airfare of 393.50 with a sample standard deviation of 50.30.

A) Find the Point estimate for the average airfare of all roundtrip flights between Philadelphia and Dallas.

B) Find t _a/2 and the margin of error (me) for 90% Confidence interval around the sample mean.

df=

t _a/2=

ME=

C) Find the 90% Confidence interval around this sample mean to estimate the average airfare of all roundtrip flights between Philadelphia and Dallas.(UCL and LCL).

D) Draw a diagram to show the point estimate, limits of the confidence interval, margin of error, and the width of the interval.

Answer 1

a)

Point estimate for the average airfare =393.50

b)df=24

t _{a/2= 1.711}

ME= 17.213

c)

90% Confidence interval : UCL =410.713

LCL =376.287

d)