Posted by mtwinkle on June 6, 2007
1. If there are x people and x seats then total
2. If x people and x seats in a cirlce then total
3. If x person, x seats, d duplicates, then total
x! / d!
4. If 3 men to be chosen from 8 men then 8C3
5. If x people and y seats, and order matters(permutation) ==> xPy
1. nPn = n!
2. nCn = 1
3. nCr = nCn-r (symmetrical property)
4. nC1 = n
5. nP1 = n
6. nCr = n! / (r!)(n-r)!
7. nPr = n!/(n-r)!