13.3 Combinations

Which of the following is an example of a combination?

• number of outcomes for a 5 digit passcode

• number of outcome for 5 students lining up at the door

• number of outcomes for 5 person group

• number of outcomes for filling the positions of president, vice president and secretary

Which formula is used for caluclating a combination?

Which is the correct set up for $_{32}C_7$ . 

•  $\frac{25!}{32!7!}$  

•  $\frac{32!}{25!}$  

•  $\frac{32!}{25!7!}$  

•  $\frac{7!}{25!}$  

Calculate ₈C_5.

Calculate $_{11}C_5$ . 

Calculate $_7C_2$ . 

You have 20 DVD's and plan on taking five with you on vacation. How many different sets of five DVD's can you take?  Choose how you would solve.

•  $\ _{20}P_5\$  

•  $\ _{20}C_5\$ 

•  $\ _5C_{20}\$  

•  $20!$ 

You want one group of 4 students to be selected from 10 students. How many different groups of four could be selected?

• 210

• 40

• 5040

• 14

You will choose 3 toppings for your sundae out of a list of 15. How many different 3-topping sundaes can be made?

• 18

• 455

• 45

• 135

You are picking one team of four players from a group of nine players. How many different teams can be made?

• 3024

• 126

• 36

• 13