Chapter 2 Flashcards
Combination formula
n!
(n-r)!r!
When order does matter, use:
Permutation formula
When order does not matter, use:
Combination formula
Permutation formula
n!
(n-r)!
When asked if “one person is chair and the rest are general members”
Multiply by the original number of people • the lost amount of people C number of people left to pick in the committee.
Ex: 4 ppl in committee, 16 in group:
16•15C3=7,280
When a problem asks # of permutations in a word:
Number of letters !
Number of repeated letters !
Ex: ALABAMA
7!
4! 210
Ex: HAWAII 6!
2!2! 180A U B
A union B
Meaning: everything that is in either one of the sets
A n B
A intersect B
Meaning: only things that are in both sets
A’ or B’
Not in A or B
Meaning: everything in the universe outside of A
A-B
Everything in A except for anything in it’s overlap w B
~(A U B)
Everything outside of A and B
~(A n B)
Everything outside of the overlap of A and B
