A very small population consists of 7 units, labeled a; b; c; d; e; f; g. How many
di�fferent samples of size 3 are there, for sampling without replacement, assuming
that
(a) samples are lists of units.
(b) samples are sets of units.
lists: P(7,3) = 7*6*5
sets: C(7,3) = P(7,3)/3!