Question: 12 people on an island

Saw this last night and i thought it would be fun to see what you guys make of it.



There are 12 people on an island, 11 of them weigh the same and 1 different in weight.
There is only a see saw on the island and no scales of any kind. The see saw can only be used 3 times.

Find the person who doesn't weigh the same as the others.

a reply to: Biigs

can you get 4 people per side

a reply to: Biigs

Six on each end.
Use heaviest side for Three on each end
Use heaviest side for One on each end.

On last go if both weigh the same then its the person not on it, or, the end that hits the ground.

?

a reply to: VoidHawk
that works

originally posted by: Borisbanger
a reply to: VoidHawk
that works

Still waiting for my free ATS T-Shirt.

originally posted by: VoidHawk
a reply to: Biigs

Six on each end.
Use heaviest side for Three on each end
Use heaviest side for One on each end.

On last go if both weigh the same then its the person not on it, or, the end that hits the ground.

?

You dont know if the one person weighs more or less than everyone else., so when you weigh 6v6 you dont know which one has the person that weighs different to the rest. (the heavier side could have a person that weighs more than the rest or the other side has someone who weighs less than the rest)

a reply to: VoidHawk

Flannel

a reply to: Biigs

Start with three groups of four each.

First, weigh groups one and two. If they balance, then the differing person is in the third group. To located them, take three of the people and weigh them against three of the people from group one whose weight is confirmed. If they also balance, then the remaining person is the target, but we still need to determine if they are heavier or lighter since that was never outlined, so you will need to weigh him against anyone from the first eight to determine that.

If the second weighing was not equal, then we know that the differentiator is one of the three, and then we can also extrapolate that they are lighter or heavier, because we know which side had the balanced persons. The seesaw raising means the differentiator is lighter and on that side and vice versa. If they balance then the third person is the target. If they do not balance we know which person is the target, because we already know if he is lighter or heavier.

If the first two groups are not balanced then that means the differentiator is in one of the groups. Take the heavier group (H) and the lighter group (L) and weigh two people from Group H and one from Group L against the other two people from Group H and one person of Group L. If they balance, the target is one of the remaining two and the final weighing will indicate who that may be. If the second weighing does not balance take the side that is heavier. Either the differentiator is one of the two Group H people or it will be one of the Group L people on the opposite side. Take the two Group H people and weigh them, if they balance, the Group L person is the differentiator, if they do not balance, then the heavier one is your 12th person.

a reply to: Biigs

Good ol' Brooklyn 99

a reply to: Biigs

This should have been specified in the OP, like it was on the show.

originally posted by: Biigs


You dont know if the one person weighs more or less than everyone else., so when you weigh 6v6 you dont know which one has the person that weighs different to the rest. (the heavier side could have a person that weighs more than the rest or the other side has someone who weighs less than the rest)

But you said they all weighed the same except the heavy person?
So there wouldn't be people who weighed less than the others... there would only be one person who weighed more.

a reply to: blupblup

I think you misread what i said, one person out of the 12 weighs a different amount, either more or less than the other 11.

If you weigh 6 one side against 6 the other, one side will be heavier and one side lighter, but since you dont know if the odd person weighs more or less you dont know which side to continue the see saw comparisons.

a reply to: Biigs

I answered this question in math class once but in involved the speed of a train.

What I would do is have 1 person sit on the see saw, and have the other 11 climb up a palm tree, and wait for a cruise ship to go by, then have the 11 people simultaneously jump onto the other end of the seesaw, sending the one person flying towards the cruise ship, and then if the one person reaches the cruise ship, he can alert the crew to the others stranded on the island and everyone can go home.

Unless the one person hated the other 11 because they were always getting mad at him for always goofing around and always getting into some kind of shenanigans... so don't send Gilligan, even though hes the lightest so you might think that would be the obvious choice, but the experienced islander realizes he will just mess it up somehow. So you choose someone more responsible, but not the Skipper cause hes too heavy. Go the middle of the road for the win, you choose the Professor! You can't send one of the women, because on an island with only 2 women of breeding age, you dont risk losing one to the sharks... and Mrs Cowl is too old and frail.

Did I get it right?

"There are 12 people on an island, 11 of them weigh the same and 1 different in weight.
There is only a see saw on the island and no scales of any kind. The see saw can only be used 3 times.

Find the person who doesn't weigh the same as the others. "

Though my logic may spark a debate regarding semantics relating to the term "used"... as all terms of any riddle that are presented and left out are used to establish the dynamics of the riddle and how it is solved, my answer should suffice.

First use of the see saw: Six people are to position themselves on each side of the see saw (12 people total). At this time, the see saw will lean to one side (doesn't matter which side). Then, during this prolonged use of the see saw, one person from each side of the see saw will dismount at a time. As soon as the see saw balances to even weight, we will know that the last two people to dismount do NOT weigh the same. We will note these two people as person A and person B (with person A weighing more than person B). Have the remaining people dismount.

Second use of the see saw: Since we know person A and person B do not weigh the same (with person A weighing more than person B), we now need to know which person weighs more or less than the remaining 10 people. For this second use of the see saw, we will weigh person A against a random person of the crowd of 10. If they weigh the same, then we know person B weighs less than the remaining crowd of 10, for he is the anomaly. If person A weighs more than the random person of the crowd of 10, we will know that person A is the one that weighs different than everyone else as he weighs more than two people, making him the anomaly.

Who needs a third use when we have semantics? This was my answer after 5 minutes of hearing the riddle on Brooklyn Nine Nine. It's enough for me... but I understand if others do not agree.

a reply to: ZeroAnnihilated

Thats how i would've done it, I dont know if you get away on technicality with that though.
And the third use would be if you wanted to know whether the person is specifically heavier or lighter. E.g.
if you weigh person A with Person C (the one we know is like the other 10) and they are the the same then you know
person B is the Heavier or lighter one, but you wouldn't know which. So you would need the third use to test him
against either person A or C and then depending what side you put Them on it would tilt either way and you could figure it out. But that would only be if the unweighted person was B. If it was A then yeh it would only take 2 moves...technically.

Look for the one person who looks a different size?

I got no time for weighing.