During a routine commercial airline flight, much of the time in the aircraft is spent waiting to take off and taxiing to an arrival gate. However, airlines also keep careful records of the actual air...

During a routine commercial airline flight, much of the time in the aircraft is spent waiting to take off and taxiing to an arrival gate. However, airlines also keep careful records of the actual air time of each flight. A random sample of the air times (in minutes) of US Airways flights from Philadelphia to Las Vegas during December 2012 was obtained, and the data are given in the following table.3

The air time for this flight is affected by the prevailing west-toeast winds and weather systems and normally takes 303 minutes. Is there any evidence to suggest the true mean air time is greater than this 303 minutes? Assume the underlying distribution is normal and use

The historical mean yield of soybeans from farms in Indiana is 31.9 bushels per acre. Following a recent dry summer, a random sample of 26 farms across the state was obtained. The mean yield in bushels per acre was x = 30.088 with s 5 4.433. Is there any evidence to suggest the lack of rain adversely affected the soybean yield SOLUTION TRAIL in Indiana? Assume the underlying population is normal and use a = 0.01.