Page 173 - Math Course 1 (Book 2)

Permutations and Combinations

Mo. 11

Lesson 7
Let’s Begin

KEY CONCEPTS:
1. Use permutations. Use a Permutation
2. Use combinations.
Example

MO. 11 - L7a
TRAVEL
Using Permutations The Reyes family will visit a complex of theme
and Combinations parks during their summer vacation. They have a
four-day pass good at one park per day; they can
choose from seven parks. How many different
ways can they arrange their vacation schedule?
Vocabulary A-Z
Let us learn some vocabulary The order in which they visit the parks is
important. This arrangement is a permutation.

7 parks Choose 4 st
7 choices for the 1 day
7 choices for the 1st day
6 choices for the 2
permutation p(7,4) = 7 ● 6 ● 5 ● 4 6 choices for the 2nd day nd day
5 choices for the 3 day
rd
An arrangement or listing in which order is = 840 5 choices for the 3rd day th
4 choices for the 4 day
4 choices for the 4th day
important is called a permutation.
There are 840 possible
combination Answer
arrangements.
An arrangement or listing where order is not
important is called a combination
NUMBERS
How many f ve-digit numbers can be made from
the digits 2, 3, 4, 5, 8, and 9 if each digit is used
only once?

p(5,5) = 5 • 4 • 3 • 2 • 1 5 choices for the 1st digit
= 120 4 choices for the 2nd digit
3 choices for the 3rd digit
2 choices for the 4th digit
Permutation Combination 1 choice remains for the
Arrangement of digits, Selection, of subjects, 5th digit
numbers, alphabets, foods, cloths, menu,
colors, letters teams
Answer 720
Clue Clue

Arrangement Committee
Schedule Group
Order Set

The order is The order is not
important important

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