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I need some help with a Counting Problem

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avatar+12 

This question has been posted here before but the answer was sadly incorrect and I used their approach with different cases and still got it wrong, any help would be appriciated.

 

I have a bag with 6 marbles numbered from 1 to 6. Mathew has a bag with 12 marbles numbered from 1 to 12. Mathew chooses one marble from his bag and I choose two from mine. In how many ways can we choose the marbles (where the order of my choices does matter) such that the sum of the numbers on my marbles equals the number on his?

 

Thanks in adavance :D

 Aug 13, 2020

5+0 Answers

 #1
avatar+22 
+1

There are 66 ways... I can come add an explanation here later. laugh

 

Hope this helps!

 Aug 13, 2020
 #2
avatar+12 
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Hi Clear,

 

thanks for your answer. I also got 66 but it was wrong lol and idk why. Perhaps there is something we are missing but im not exactly sure. :)

Kobe4Life  Aug 13, 2020
 #3
avatar+22 
+1

Huh! Maybe someone smarter than me can come help out.

Clear  Aug 13, 2020
 #4
avatar+1490 
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Important: " ... where the order of my choices does matter "

 

If I understand the question correctly, you have only 15 choices:

 

1      1+2, 1+3, 1+4, 1+5, 1+6

 

2      2+3, 2+4, 2+5, 2+6

 

3      3+4, 3+5, 3+6

 

4      4+5, 4+6

 

5      5+6  

 

So, the answer is 15  wink

 Aug 13, 2020
 #5
avatar+12 
0

Hi dragan, 

 

thank you for the answer after me getting it wrong a few times i quit and the answer was 30, I forgot to copy down the solution sorry for that.

Kobe4Life  Aug 14, 2020

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