Lesson 60- Combinations

Combination's  have no order and Permutations do have an order.

Example 1:
If 5 sprinters compete in a race, how many different ways can the medals for first, second and third place be awarded?
5 x 4 x 3 = 5p3 = 60  genine
This is an example of a permutation of 5 objects taken 3 at a time

If 5 sprinters compete in a race and the fastest 3 qualify for the relay team, how many different relay teams can be formed?
YYY NN     Yes: succeed   No: fail          5!/ 3! 2! = 120/ 12  = 10
This is an example of a combination of 5 objects taken 3 at a time

Combinations:
An unordered arrangement if distinct objects is called a combination
The number if combination's of n distinct objects taken r at a time is nCr