Question 557950
number of students = 800
number of faculty members = 50
number of administrators = 150
total = 1000
assuming the selection was random, then:
probability it would be a student would be 800 / 1000
probability it would be a faculty member would be 50 / 1000
probability it would be an administrator would be 150 / 1000
probability it would be a faculty member or an administrator would be 200 / 1000
probability it would be anyone except an administrator would be 850 / 1000
the probability it would be any number of a certain type is the number of occurrences of that type divided by the number of total occurrences.
in the case of the faculty member or administrator, this assumes that a person is not a faculty member and an administrator at the same time. 
the generic term for this is that each type is mutually exclusive which means that you can't have a member of one type being also a member of the other type.