AA (Federal Aviation Administration) records show an average flight delay of 19 minutes for all domestic flights in 2009. A random sample of 150 U.S. Air flights results in a mean flight delay of 21 minutes with a sample standard deviation of 10.
1.Using the 7 steps in significance testing, determine whether there is a statistically significant difference between U.S. Air and the national average such that U.S. Air has longer flight delays. Show all 7 steps.