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Overview
Statistics
17. CC.HSS.CP.B.9
17.1 Permutations
Permutations
A permutation counts the ordered arrangements of r items chosen from n, using nPr = n! divided by (n minus r)!.
What You'll Learn
A permutation counts ordered arrangements of r items chosen from n, where order matters.
The formula is nPr = n! divided by (n minus r) factorial.
Example: 4P2 = 4!/(4-2)! = 24/2 = 12 ordered arrangements.
Permutations use factorial notation as their building block.
If order doesn't matter, use a combination instead of a permutation.
What You'll Practice
1
Selecting and arranging students for different leadership positions
2
Arranging books on a shelf when order matters
3
Determining when to use permutation versus combination in word problems
4
Calculating nPr values using the permutation formula
Why This Matters
Permutations are essential for solving real-world problems involving passwords, seating arrangements, scheduling, and any situation where order matters. This foundational counting principle appears in probability, statistics, computer science, and is crucial for standardized tests and higher-level math courses.
Before You Start — Make Sure You Can:
This Unit Includes
2 Video lessons
Practice exercises
Learning resources
Skills
Permutations
Counting Principles
Combinatorics
Order Matters
nPr Formula
Probability
Problem Solving
CO Curriculum Aligned