P&C Flashcards
1
Q
When do u use addition principle?
A
If A and B cannot happen at the same time, there are m+n ways to perform event A OR event B
2
Q
Multiplication principle
A
There are m x n ways to perform event A and then event B
3
Q
No of ways of arranging n DISTINCT obj along a line
A
n!
4
Q
No. Of ways of arranging n obj along a line such that n1 of them are identical, n2 of them are identical….
A
n! / (n1!n2!…nk!)
5
Q
Choosing r obj from n distinct obj
A
nCr = n! / r! (n-r)!
6
Q
Choosing r obj from n distinct obj, then arranging them
A
nCr x r!
