9-5 Combinations (pgs 387-390)

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9-5 Combinations(pgs 387-390)

• Indicator- D7

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• Combinations- an arrangement where order does not
  matter
• Example 1
• How many different two topping pizzas
• can be made from 5 toppings?
• (Does it matter if you pick pepperoni
• then sausage or sausage then pepperoni?)
• 5C2
• Find the permutation of the 5 toppings-
  5X4 20
• by the ways to arrange two toppings
  2X1 2
• There are 10 different two topping pizzas.

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• Example 2
• Jen can invite three of the 12 girls in her class
  to a party. How many different arrangements can
  there be?
• (does it matter if youre picked 1st or 3rd?)
• 12C3 12X11X10 1320 220
• 3! 6
• There are 220 different
• combinations of girls that
• can be invited.

4

• How many ways can a president, vice-president and
  secretary be chosen from the 10 students on
  student council?
• (Are the chances of being president the same as
  being secretary?)
• This is a .. Permutation
• 10P3 10X9X8 720 Ways
• There are 720 ways to choose officers.

5

• Decide if each problem is a permutation or
  combination then solve.
• 8 players are playing each other in a checker
• tournament. How many games will be played?
• 8 C 2
• How many ways to pick 6 starters from a 12
• member volleyball team?
• 12 C 6
• How many ways can you arrange the letters in the
  word
• word?
• 4 P4

W-O-R-D
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• 9-5/389-390/ 7- 22, 27-32