This topic explain what is permutations and how to apply them.
At the end of this lesson, you should be able to
What is Permutation?
A permutation is an arrangement of N objects in a specific order. Note that the order is important.
For example, suppose we have a set of three letters: A, B, and C. We might ask how many ways we can arrange 2 letters from that set. The complete list of possible permutations would be: AB, AC, BA, BC, CA, and CB.
Another example. How about the PIN for my bank account? Suppose the PIN to my account is 8-9-10. If I want to access my bank account through the ATM, I do need to care about the order of those numbers. “10-9-8” would not access my account. Neither would “9-10-8.” It has to be exactly 8-9-10. The order is important.
Basic Permutations
Example 1:
A business man has 4 dress shirts and 7 ties. How many different shirt/tie outfits can he create?
Solution: For each outfit, he can choose one of four shirts and one of seven ties. Therefore, the business man can create (4 x 7) = 28 different shirt/tie outfits.
Example 2:
A female student has the following in her wardrobe: 4 blouses, 7 skirts & 6 pairs of shoes. How many possible ways can she dress herself up?
Solution: Student can choose any one of the 4 blouses, 7 skirts & 6 pairs of shoes. Therefore, possible ways to dress up = 4 x 7 x 6 = 168.
Permutation Calculations for Distinct Objects