How many different ways can a group of students be hired to work a survey?

The Statistics Survey Centre wishes to hire some undergraduates to help in a phone survey. On the call list are 6 second-year students, 3 third-year and 3 fourth-year students. Policy is to always hire at least one third year and one fourth year student. Other than that as many students as are needed can be hired without restriction.

The Statistics Survey Centre wishes to hire some undergraduates to help in a phone survey. On the call list are 6 second-year students, 3 third-year and 3 fourth-year students. Policy is to always hire at least one third year and one fourth year student. Other than that as many students as are needed can be hired without restriction.