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BDMO REGIONAL 2015

Posted: Mon Feb 06, 2017 3:39 pm
by Math Mad Muggle
please, help me to this.....

Re: BDMO REGIONAL 2015

Posted: Mon Feb 06, 2017 5:02 pm
by NOBODY
2 ,
118 AND 8

Re: BDMO REGIONAL 2015

Posted: Mon Feb 06, 2017 11:01 pm
by Absur Khan Siam
Solution:
Note that there exists a number for each number such that the sum is $126$,except $2$.Thus if we take
$14$ number,we can ensure that the sum of any two number is $126$.

Re: BDMO REGIONAL 2015

Posted: Tue Feb 07, 2017 4:32 pm
by SMMamun
How did you find 14 number(s)? Did you rather mean 24? How can you find the sum 126 if you take one of the numbers to be 3?

Anyway, the phrase "the sum of any two among them" is ambiguous and does not seem to clarify what the question setters actually asked for.

Re: BDMO REGIONAL 2015

Posted: Tue Feb 07, 2017 5:00 pm
by Absur Khan Siam
I think the statement should be "There exists a pair such
that the sum is $126$"

Re: BDMO REGIONAL 2015

Posted: Mon Mar 27, 2017 8:14 pm
by Zawadx
NOBODY wrote:2 ,
118 AND 8
You do have a point xD

The question is not properly stated. A better question would be 'Upto how many numbers must the sequence $2,3,8,13,18,23, \dots ,118$ be continued to ensure that there exists at least one pair with sum $126$'. Though that is still not perfect because the sequence is not well defined. I mean, no well-known sequence starts with $2,3,13,18,23$ The closest we have is this one :P

Or maybe the question is perfect and they want to see who has the common sense to give 2 as the answer.