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Source: — Problem Solving |

by CSASHISHPANDAY » Wed Jul 25, 2012 5:12 am
If n is a positive integer between 1 and 99, inclusive, what is the probability that n(n+1) is a multiple of 3?

1) 1/4
2) 1/3
3) 1/2
4) 2/3
5) 5/6
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by RyanJW » Wed Jul 25, 2012 6:19 am
I think this one is [spoiler]4) 2/3 [/spoiler]

But I followed a weird path to get that answer so would not be surprised if it's wrong. Looking forward to the answer.
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by eagleeye » Wed Jul 25, 2012 6:45 am
CSASHISHPANDAY wrote:If n is a positive integer between 1 and 99, inclusive, what is the probability that n(n+1) is a multiple of 3?

1) 1/4
2) 1/3
3) 1/2
4) 2/3
5) 5/6
I've posted a solution here:

https://www.beatthegmat.com/probability- ... tml#488603
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