2. Twenty people entered the 5000 meter swim at a local pool.
a. How many ways can places 1st – 6th be awarded?
b. How many ways can the top 8 be determined

Question

2.	Twenty people entered the 5000 meter swim at a local pool. 
a.	How many ways can places 1st – 6th be awarded? 
b.	How many ways can the top 8 be determined

mathstudent55 · Answer

This is a question in which the order matters.
Does that make it a combination or permutation problem?

anonymous · Answer

permutation

mathstudent55 · Answer

Correct.
You need the formula for choosing r items out of n items.

$_nP_r = \dfrac{n!}{(n - r)!}$

mathstudent55 · Answer

In your case, for part a, n = 20, and r = 6.
For part b, n = 20, and r = 8.

anonymous · Answer

okay for part A: 
20P6 = 20/(20-6) = 20/14 =

20P8 = 20/(20-8) = 20/12 = 

do you think you could help me understand what to do from here? thank you so much for your help by the way

anonymous · Answer

the second equation is for part b sorry

mathstudent55 · Answer

Don't forget the factorial signs.

mathstudent55 · Answer

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