Question

N how many ways can a sample (without replacement) of 7 items be selected from a population of 13 items?

Answer 1

In other words, how can a group of 7 people be chosen from 13?
Combinations = n! / [r! * (n-r)!]
Combinations = 13*12*11*10*9*8*7! / 7! * (13 -7)!
Combinations = 13*12*11*10*9*8*7! / 7! * 6!
Combinations = 13*12*11*10*9*8 / 6!
Combinations = 13*11*2*3*2
Combinations = 1,716

Source:
http://www.1728.org/combinat.htm