Kako izračunati Combinations Permutations
Kaj je Combinations Permutations?
Combinations count ways to choose items where order does not matter. Permutations count ways where order does matter. Both use factorials and appear in probability, statistics, and combinatorics.
Navodila po korakih
- 1Permutations (order matters): P(n,r) = n! / (n−r)!
- 2Combinations (order irrelevant): C(n,r) = n! / (r!(n−r)!)
- 3Rule of thumb: if you can swap two items and get a different result, use permutations
Worked Examples
Vnos
Choose 3 from 10 (order matters)
Rezultat
720
P(10,3) = 10×9×8 = 720
Vnos
Choose 3 from 10 (order irrelevant)
Rezultat
120
C(10,3) = 720/6 = 120
Vnos
Lotto: 6 from 49
Rezultat
13,983,816
C(49,6)