Can you solve the prisoner boxes riddle? - Yossi Elran

10,980,294 views ・ 2016-10-03

TED-Ed


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Prevoditelj: Tomas Kurbanović Recezent: Sanda L
00:06
Your favorite band is great at playing music,
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Tvoj omiljeni bend je odličan u sviranju,
00:10
but not so great at being organized.
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ali ne tako dobar kada se treba organizirati.
00:13
They keep misplacing their instruments on tour,
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Stalno zameću svoje instrumente na turneji,
00:16
and it's driving their manager mad.
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a to izluđuje njihovog menadžera.
00:18
On the day of the big concert,
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Na dan velikog koncerta,
00:20
the band wakes up to find themselves tied up
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članovi benda probude se zatočeni
00:22
in a windowless, soundproof practice room.
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u zvučno izoliranoj sobi za probe bez prozora.
00:26
Their manager explains what's happening.
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Njihov menadžer objasni im što se događa.
00:28
Outside, there are ten large boxes.
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Vani je deset velikih kutija.
Svaka sadrži jedan od vaših instrumenata,
00:32
Each contains one of your instruments,
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00:34
but don't be fooled by the pictures - they've been randomly placed.
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ali ne dajte da vas slike zavaraju; postavljene su nasumično.
00:39
I'm going to let you out one at a time.
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Puštat ću vas jednog po jednog.
00:42
While you're outside, you can look inside any five boxes
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Dok ste vani, možete pogledati u bilo kojih pet kutija,
00:46
before security takes you back to the tour bus.
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prije nego vas zaštitari vrate u autobus.
00:50
You can't touch the instruments
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Ne smijete dirati instrumente
00:51
or in any way communicate what you find to the others.
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ili na neki način drugima pokušati reći što ste našli.
00:55
No marking the boxes, shouting, nothing.
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Nema označavanja kutija, vikanja, ničega.
00:59
If each one of you can find your own instrument,
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Ako svatko od vas uspije naći svoj instrument,
01:02
then you can play tonight.
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večeras možete svirati.
01:04
Otherwise, the label is dropping you.
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U suprotnom, diskografska kuća raskida ugovor s vama.
01:07
You have three minutes to think about it before we start.
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Imate tri minute za razmišljanje prije početka.
01:10
The band is in despair.
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Bend je u očaju.
01:12
After all, each musician only has a 50% chance of finding their instrument
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Svaki glazbenik ima samo 50% šanse za pronalaženje svog instrumenta,
01:16
by picking five random boxes.
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bude li birao pet nasumičnih kutija.
01:19
And the chances that all ten will succeed are even lower -
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Šanse da svi uspiju čak su i manje;
01:22
just 1 in 1024.
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samo 1 : 1024.
01:25
But suddenly, the drummer comes up with a valid strategy
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Iznenada, bubnjar je iznio razumnu strategiju
01:28
that has a better than 35% chance of working.
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koja ima više od 35% šanse za uspjeh.
Možeš li shvatiti što je predložio?
01:33
Can you figure out what it was?
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01:35
Pause the video on the next screen if you want to figure it out for yourself!
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Pauziraj video na idućem zaslonu ako želiš sam riješiti zagonetku.
01:43
Answer in: 3
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Odgovor za: 3
01:45
Answer in: 2
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Odgovor za: 2
01:46
Answer in: 1
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Odgovor za: 1
01:47
Here's what the drummer said:
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Bubnjar je rekao sljedeće:
01:49
Everyone first open the box with the picture of your instrument.
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Svatko neka prvo otvori kutiju sa slikom svojeg instrumenta.
01:53
If your instrument is inside, you're done.
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Ako je unutra tvoj instrument, gotov si.
01:55
Otherwise, look at whatever's in there,
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U suprotnom, pogledaj što je u kutiji
01:57
and then open the box with that picture on it.
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i zatim otvori kutiju koja ima sliku tog instrumenta.
02:00
Keep going that way until you find your instrument.
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Nastavi dok ne nađeš svoj instrument.
02:03
The bandmates are skeptical,
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Članovi benda su skeptični,
02:05
but amazingly enough, they all find what they need.
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no, začuđujuće, svi nađu što trebaju.
02:08
And a few hours later, they're playing to thousands of adoring fans.
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Nekoliko sati kasnije, sviraju za tisuće svojih obožavatelja.
02:12
So why did the drummer's strategy work?
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Zašto je bubnjarova strategija djelovala?
02:14
Each musician follows a linked sequence
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Svaki glazbenik prati povezani niz
02:17
that starts with the box whose outside matches their instrument
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koji počinje kutijom čija slika odgovara njihovom instrumentu
02:20
and ends with the box actually containing it.
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i završava kutijom koja ga sadrži.
Opazi da bi se vratili na početak kada bi nastavili,
02:25
Note that if they kept going, that would lead them back to the start,
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02:28
so this is a loop.
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dakle, ovo je petlja.
02:30
For example, if the boxes are arranged like so,
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Na primjer, da su kutije ovako poslagane,
02:32
the singer would open the first box to find the drums,
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pjevačica bi otvorila prvu kutiju i našla bubnjeve,
02:36
go to the eighth box to find the bass,
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otišla do osme kutije i našla bas gitaru
02:38
and find her microphone in the third box,
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i našla mikrofon u trećoj kutiji,
02:41
which would point back to the first.
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koja bi je vodila natrag do prve.
02:43
This works much better than random guessing
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Ovo djeluje puno bolje od nasumičnog pogađanja,
02:46
because by starting with the box with the picture of their instrument,
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jer ako započne kutijom sa slikom svojeg instrumenta,
02:49
each musician restricts their search to the loop that contains their instrument,
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svaki glazbenik ograničava potragu na petlju koja sadrži njihov instrument
02:54
and there are decent odds, about 35%,
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i postoji pristojna mogućnost, oko 35%,
02:57
that all of the loops will be of length five or less.
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da će sve petlje biti duge pet ili manje koraka.
03:02
How do we calculate those odds?
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Kako smo izračunali tu mogućnost?
03:03
For the sake of simplicity, we'll demonstrate with a simplified case,
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U svrhu jednostavnosti, demonstrirat ćemo na pojednostavljenom slučaju;
03:07
four instruments and no more than two guesses allowed for each musician.
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četiri instrumenta i ne više od dva pokušaja po glazbeniku.
03:13
Let's start by finding the odds of failure,
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Počnimo pronalaženjem mogućnosti neuspjeha,
03:16
the chance that someone will need to open three or four boxes
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slučajem da će netko morati otvoriti tri ili četiri kutije,
03:19
before they find their instrument.
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prije nego pronađe svoj instrument.
03:21
There are six distinct four-box loops.
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Postoji šest jedinstvenih petlji s četiri kutije.
03:24
One fun way to count them is to make a square,
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Jedan zabavan način da ih izbrojiš jest da napraviš kvadrat.
03:27
put an instrument at each corner,
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Stavi po jedan instrument u svaki kut
03:29
and draw the diagonals.
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i povuci dijagonale.
03:31
See how many unique loops you can find,
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Vidi koliko jedinstvenih petlji možeš naći,
03:34
and keep in mind that these two are considered the same,
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ali imaj na umu da se ove dvije smatraju jednakima,
03:38
they just start at different points.
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samo kreću iz različite točke.
03:40
These two, however, are different.
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Međutim, ove su dvije različite.
03:42
We can visualize the eight distinct three-box loops using triangles.
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Možemo si predočiti osam različitih petlji s tri kutije koristeći trokute.
03:47
You'll find four possible triangles
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Naći ćeš četiri moguća trokuta,
03:49
depending on which instrument you leave out,
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ovisno o instrumentu kojeg izostaviš,
03:52
and two distinct paths on each.
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i dva različita puta na svakom.
03:54
So of the 24 possible combinations of boxes,
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Dakle, od 24 mogućih kombinacija kutija,
03:58
there are 14 that lead to faliure,
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14 ih vodi k neuspjehu,
04:00
and ten that result in success.
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a 10 rezultira uspjehom.
04:03
That computational strategy works for any even number of musicians,
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Ta računska strategija vrijedi za sve parne brojeve glazbenika,
04:08
but if you want a shortcut,
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no, ako želiš kraticu,
04:09
it generalizes to a handy equation.
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može se svesti na korisnu jednadžbu.
04:13
Plug in ten musicians, and we get odds of about 35%.
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Uključi deset glazbenika i dobit ćemo šanse od oko 35%.
04:18
What if there were 1,000 musicians?
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Što kada bismo imali tisuću glazbenika?
04:20
1,000,000?
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Milijun?
04:21
As n increases, the odds approach about 30%.
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Kako se n povećava, šanse se približavaju 30-ak posto.
04:26
Not a guarantee, but with a bit of musician's luck, it's far from hopeless.
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Nije garancija za uspjeh, no uz malo sreće, stvar je daleko od beznadne.
04:32
Hi everybody, if you liked this riddle, try solving these two.
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Ako vam se svidjela ova zagonetka, pokušajte riješiti ove dvije.
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