It has been claimed that flattening (“rolling”) the barrel of a graphite baseball bat can stretch the fibers and result in a pitched baseball being returned faster than with a regulation bat. This was a controversial topic during the 2009 baseball College World Series. Assume that data file XR11013 describes the results of a controlled test measuring the return speeds of balls pitched to a flattened bat and a regulation bat, respectively. Based on these sample results, and using a suitable one-tail test at the 0.05 level, was the mean return speed for the flattened bat significantly greater than for the regulation bat? Identify and interpret the p-value for the test.
A computer and statistical software.