JB Permutation & Combination Flashcards
1
Q
nPr
A
n!/(n-r)!
2
Q
nCr
A
n!/[r! x (n-r)!]
3
Q
Order matters
A
Permutation
4
Q
Order doesn’t matter
A
Combination
5
Q
Arrangements
A
Permutation
6
Q
Grouping or selection
A
Combination
7
Q
Arrangement of n different objects in straight line
A
n!
8
Q
Arrangement of n different objects in a circle
A
(n-1)!
9
Q
Arrangements for Mississippi
A
11!/[4! x 4! x 2!]
10
Q
Number of arrangements when some objects are together
eg - [a v e] d f g : ave need to be together
A
Arrangement of all objects considering box as single object x arrangement inside box
= 4! x 3!
