Permutation and Combination

[naveenhv]

What is the number of different committees of 4 people that can be selected from a group of 10 people?

a) 20

b) 40

c) 80

d) 120

e) 210

[vikram4689]

This is a direct question of Combinatons.
C (n,r) = n ! / [ r ! * (n! - r !) ]

n = total no of entities = 10 (here)
r = no of entities to be selected = 4 (here)

solve by substituting the values. Answer is 210, e)

[jnelson0612]

This is a direct question of Combinatons.
C (n,r) = n ! / [ r ! * (n! - r !) ]

n = total no of entities = 10 (here)
r = no of entities to be selected = 4 (here)

solve by substituting the values. Answer is 210, e)

Correct. I use the formula:

Pool!
In! Out!

It yields the same numbers as the formula above, but I think it's easier to use (or at least it is for me). In this case it would be:
10!
4! 6!