Determine whether the numerical value is a parameter or a statistics (and explain):

a) A recent survey by the alumni of a major university indicated that the average salary of 10,000 of its 300,000 graduates was 125,000.

b) The average salary of all assembly-line employees at a certain car manufacturer is $33,000.

c) The average late fee for 360 credit card holders was found to be $56.75