From the set of numbers s={1, 2, 3, 4}, how many minimum numbers must be selected to guarantee that at least one pair of these numbers has a sum equal to 7?
why the answer is not 4 because if we pick 4 numbers from the give set that means we are picking all the 4 numbers so we always pick 3 and 4 which sum up to 7 which is the required sum
hi @snehacpcb_6a154f5c45187387
If it is possible to take multiple 1’s 2’s 3’s or 4’s
then, taking 2 any number of times will never give 7 as 2n != 7 for any n
Thus its now clear that you can take only once each number, taking n=1,2,3 would not guarantee 7 as sum
for n=3 one can select 1,2,3 (here no pair is summed to 7)
but n=4 guarantee
so go with 4
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