The seesaw is filled with nine pairs of identical twins. All the kids weigh the same (e.g., they all weigh 100, but the actual numbers are irrelevant), except for one set of twins. They are still identical twins, so they weigh the same as each other, but not the same as the other 16 kids (e.g., these two children each weigh 101, but, again, the actual numbers are irrelevant). If (exactly) four kids on one side switch positions with four other kids on the other side to balance the seesaw, which is the odd pair?
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1$\begingroup$ So you're saying there is one pair of twins that weighs a different amount, and the rest weigh the same? $\endgroup$– Gabriel BurnsNov 7, 2016 at 17:25
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$\begingroup$ Yes 1 twin. 2 kids with same weight but unlike the rest causing the tilt $\endgroup$– TSLFNov 7, 2016 at 17:31
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1$\begingroup$ Just to fully clarify. Everyone always weighs the same as their twin, and everyone on the seesaw is a twin of someone else on the seesaw. In addition to weighing the same as their twin, everyone here actually has the same weight as everyone else, except for one pair that weigh differently (but still the same as each other)? Or is it just that every person with the same letter has the same weight as every other person with that letter (a less narrow constraint)? $\endgroup$– Rubio ♦Nov 7, 2016 at 17:48
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1$\begingroup$ Have you taken into account the position on the seesaw beam? A kid that's 20kg heavier than the rest will have more effect on the outermost position of the seesaw than one that's at the innermost position. $\endgroup$– Ian MacDonaldNov 7, 2016 at 18:20
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2$\begingroup$ Wish I could ^vote twice, after seeing the solution, once for each side of this clever puzzle $\endgroup$– whiskrsNov 7, 2016 at 21:01
1 Answer
The "odd" pair is
the O twins.
The way to balance the seesaw
is to change
ttl+eoevnn . wweove+leeto
tWO+eLevEn = TweLve+ONe(using capital letters to show the four and four that switched). This cleverly "balances" the seesaw because it spellsTWO+ELEVEN = TWELVE+ONE
, i.e., 2+11=12+1. After this switch, the O twins are both third from the end, so the seesaw balances even though they don't weigh the same as the others. That is the only letter that is moved into a symmetric configuration.
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1$\begingroup$ I expected that somebody else would get it in the 10 minutes it took me to type the explanation. $\endgroup$ Nov 7, 2016 at 17:54
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$\begingroup$ @Peregine Rook- That is the Odd Twin. I expected it to be answered at least an hour and you are typing slow. Nice work. $\endgroup$– TSLFNov 7, 2016 at 18:21
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$\begingroup$ What makes
WWO+eLevnn ^ TTeLve+Oee
unbalanced? $\endgroup$ Nov 7, 2016 at 18:51 -
$\begingroup$ @IanMacDonald: It's lateral thinking wordplay. WWO+eLevnn ^ TTeLve+Oee is gibberish; my solution balances the seesaw in a wordplay way. $\endgroup$ Nov 7, 2016 at 18:54
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1$\begingroup$ @IanMacDonald finding two+eleven = twelve+one is balanced reveals the twins that are different. The worldplay shows us which twins are wrong. $\endgroup$ Nov 8, 2016 at 0:58