12.6. Counting with Permutations and Combinations http://www.ck12.org
12.6 Counting with Permutations and Combina-
tions
Here you will review counting using decision charts, permutations and combinations.
Sometimes it makes sense to count the number of ways for an event to occur by looking at each possible outcome.
However, when there are a large number of outcomes this method quickly becomes inefficient. If someone asked
you how many possible regular license plates there are for the state of California, it would not be feasible to count
each and every one. Instead, you would need to use the fact that on the typical California license plate there are four
numbers and three letters. Using this information, about how many license plates could there be?
Watch This
MEDIA
Click image to the left for use the URL below.
URL: http://www.ck12.org/flx/render/embeddedobject/62275http://www.youtube.com/watch?v=qJ7AYDmHVRE James Sousa: The Counting Principle
MEDIA
Click image to the left for use the URL below.
URL: http://www.ck12.org/flx/render/embeddedobject/62277http://www.youtube.com/watch?v=JyRKTesp6fQ James Sousa: Permutations
MEDIA
Click image to the left for use the URL below.
URL: http://www.ck12.org/flx/render/embeddedobject/62279http://www.youtube.com/watch?v=SGn1913lOYM James Sousa: Combinations
Guidance
Consider choiceAwith three options(A 1 ,A 2 ,A 3 )and choiceBwith two options(B 1 ,B 2 ). If you had to choose an
option fromAand then an option fromB, the overall total number of options would be 3· 2 =6. The options are
A 1 B 1 ,A 1 B 2 ,A 2 B 1 ,A 2 B 2 ,A 3 B 1 ,A 3 B 2.