PERMUTATION COMBINATION

WHAT IS A FACTORIAL ?

• This is a factorial sign !
• A factorial works like this 5!
• Equals 5x4x3x2x1=120 so 5!
• Equals 120

PERMUTATION

PERMUTATION

• Formula
• N!
• ----------
• (N-R)!
• That looks confusing here is what it means

THE BETTER FORMULA

• Arrangement of (n)objects (r) at a time
• N!
• -------------
• (N-R)!

PROBLEM

• Bob's family members always hug each other when they
• Say hello. If ten of them meet how many hugs will there be

ANSWER

COMBINATION

• Order doesn't matter
• So a,b,c and c,b,a are the same
• Because the order doesn't matter

Combination formula
N!
-----------------
R!(N-R)

Untitled Slide

• Bob's family members always hug each other when they
• Say hello. If ten of them meet how many hugs will there be

ANSWER

1.
From a group of 7 men and 6 women, five persons are to be selected to form a committee so that at least 3 men are there on the committee. In how many ways can it be done?