A simple random sample of 150 San Antonio area policemen found that the average time these police officers had worked for the police department was 16 years with a standard deviation of 5 years. Ten years ago the average amount of time policemen stayed on the job was 15 years. The city wants to find out if this data shows evidence that the average has increased.

What would be the best type of significance test for this situation?

Determine and Write a null and alternative hypothesis that can be used for the city’s research.