Problem
Some experts on the film industry state that the industry historically returns 12 per cent a year. The table includes the U.S. return on investment (ROI) (simply defined as the difference between total US box- office gross and budget divided by budget, ignoring any form of discounting) for each movie in the data set.
a) Provide a 95 per cent interval for the mean US ROI of movies.
b) Run a test to see if the US ROI is significantly larger than the 12 per cent cited (Ho: mu<=0.12)