Lesson 2C: Permutations

Recall Example 1 in Lesson 2A in which customers were asked to choose an ice cream cone. The problem was to determine how many arrangements a customer could have when given one choice each of cone, ice cream, and topping. In this example, you must consider the choices in a specific order cone - ice cream - topping . This makes sense because you would not hold the ice cream in your hand and then put the cone on top of it! In this case, order matters.

Because you have to choose cone - ice cream - topping in a specific order , this problem is called a permutation . Permutations are the focus of this Training Camp.

 

By the end of this lesson, you should be able to

	determine, the number of permutations of n elements taken r at a time
	represent the number of arrangements of n elements taken n at a time, using factorial notation
	determine the number of permutations of n elements taken n at a time where some elements are not distinct

 

Use the flowchart to help you throughout this lesson. Click on the image to enlarge.