Aim #10-7: How do we use the
permutation formula?
 A permutation is an ordered arrangement of
items that occurs when:
 No item is used more than once.
 The order of the arrangement makes a
difference.
Example 1: Using the Formula for
Permutations
Check for Understanding:
Example 2: Using the Formula
 You need to arrange seven of your favorite
books along a small shelf . In how many
different ways can you arrange the books,
assuming that the order of the books makes a
difference to you?
Check for Understanding:
 In how many ways can six books be lined up
along a shelf?
How do we distinguish between
combinations and permutations?
 A combination occurs when:
 The items are selected from the same group.
 No item is used more than once.
 The order of the items makes no difference.
Note:
 Permutations problems involve situations
which order matters.
Example 3:
Solution:
Check for Understanding:
 For each of the following problems explain if
the problem is one involving permutations or
combinations.
1. How many ways can you select 6 free
DVD’s from a list of 200 DVDs?
2. In a race in which there are 50 runners and
no ties, in how many ways can the first three
finishers come in?
A Formula for Combinations
Example 4:
 A three-person committee is needed to study
ways of improving public transportation. How
many committees could be formed from the
eight people on the board of supervisors?
Check for Understanding:
 From a group pf 10 physicians, how many
ways can four people be selected to attend a
conference on acupuncture?
Example 8:
Check for Understanding:
 How many different 4-card hands can be
dealt from a deck that has 16 different cards?
Summary:
Answer in complete sentences.
Explain what is a permutation.
How do permutations and combinations differ?
How do you solve each?