Twenty-one computer programmers from IT firms around the country were selected at random. Each was asked to write code in C++ and in Java for a specific application. The runtime (in seconds) for each...

Twenty-one computer programmers from IT firms around the country were selected at random. Each was asked to write code in C++ and in Java for a specific application. The runtime (in seconds) for each program, by computer language, was recorded.

A consultant working for a State Police barracks contends that service weapons will fire with a higher muzzle velocity if the barrel is properly cleaned. A random sample of Glock 9-mm handguns was obtained, and the muzzle velocity (in feet per second) of a single shot from each gun was measured. Each gun was professionally cleaned, and the muzzle velocity of a second shot (with the same bullet type) was measured. The data are given in the following table.