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Math Challenge II-A Combinatorics Chapter 5 Practice Question 5.21 Part b)

 
 
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Math Challenge II-A Combinatorics Chapter 5 Practice Question 5.21 Part b)
by Zeyin Wu - Sunday, September 19, 2021, 6:57 AM
 

Referring to Math Challenge II-A Combinatorics Chapter 5 Practice Question 5.21 Part b)

Why is the answer shown on the website 29 choose 15? Shouldn't it be 29 choose 15 and then minus 15, since there are 15 ways in which all 15 passengers will get off the train at the same stop?

Thanks!

 
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Re: Math Challenge II-A Combinatorics Chapter 5 Practice Question 5.21 Part b)
by John Lensmire - Monday, September 20, 2021, 10:39 AM
 

Hi Zeyin. The solution for the quiz has now been updated to make the final solution more clear. You are correct it is (29 choose 15) - 15. Thanks for letting us know!

 
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