11.7 Combinations

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11.7 Combinations

• Pre-Algebra B

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Key Terms

• Combination _____________________________________
  _________________________________________

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Example 1 Listing Combinations

• A basketball league has 5 teams. Two of the
  teams are chosen to play one another. List and
  count the different possible matchups of the
  basketball teams.

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Checkpoint

• You want to buy 4 different CDs. You can afford
  to buy only 3 of them. How many combinations of
  CDs can you buy?

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Combinations

• N number of objects
• R at a time
• nCr
• Example
• 9C5

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Example 2 Counting Combinations

• You need to write 4 book reports for your English
  class. Your teacher gives the class a list of 7
  books from which to choose. How many different
  groups of 4 books can you choose from the list?

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Checkpoint

• Find the number of Combinations.
• 1.) 6C2
• 2.) 8C3
• 3.) 5C5
• 4.) 7C2

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Permutation Vs. Combination

• There are 30 dogs in a dog show. Blue ribbons
  are awarded to the top 3 dogs. How many
  different groups of dogs can receive blue
  ribbons?
• There are 30 runners in a cross country race.
  How many different groups of runners can finish
  first, second, and third?