The average salary for all 27 Arizona Diamondbacks in the 2005 baseball season was $2,308,488, with a standard deviation of $3,427,508. The corresponding population, all National League baseball players in 2005, earned an average salary of $2,585,804, with a standard deviation of $3,500,708. Does the salary of the Diamondbacks players differ from that of all players in the National League?

1. Name of correct statistical test:
2. Why is this test correct?