Counting Techniques, Permutation & Combination Flashcards
1
Q
Suppose there are n₁ ways for E₁ to occur, and n₂ ways for event E₂ to occur we cannot do both E₁ and E₂.
A
Addition Principle
2
Q
Suppose there are n₁ ways for E₁ to occur, and each possible way that E₁ occurs allows exactly n₂ ways for event E₂ to occur.
A
Multiplication Principle
3
Q
The number of different ways we can arrange a number of items.
A
Permutations
4
Q
Permutations of n object taking r at a time
A
nPr = n!/(n-r)!
5
Q
Permutations of Identical objects
A
P= n!/r₁!r₂!r₃!*r₄!…
6
Q
Circular Permutations
A
P(n)=(n-1)!
7
Q
Arrangement of objects where the order in which the objects are selected does not matter.
A
Combination
8
Q
“Selection”
A
Combination
9
Q
“Arrangement”
A
Permutations
10
Q
Combination
A
nCr = n!/(n-r)!r!
