Can you steal the most powerful wand in the wizarding world? - Dan Finkel

907,487 views ใƒป 2023-01-26

TED-Ed


ืื ื ืœื—ืฅ ืคืขืžื™ื™ื ืขืœ ื”ื›ืชื•ื‘ื™ื•ืช ื‘ืื ื’ืœื™ืช ืœืžื˜ื” ื›ื“ื™ ืœื”ืคืขื™ืœ ืืช ื”ืกืจื˜ื•ืŸ.

ืชืจื’ื•ื: Vlady Lobak ืขืจื™ื›ื”: zeeva livshitz
00:06
The fabled Mirzakhani wand is the most powerful magical item ever created.
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ืฉืจื‘ื™ื˜ ืžื™ืจื–ื—ืื ื™ ื”ืื’ื“ื™ ื”ื•ื ื”ืคืจื™ื˜ ื”ืงืกื•ื ื”ืขื•ืฆืžืชื™ ื‘ื™ื•ืชืจ ืฉื ื•ืฆืจ ืื™ ืคืขื.
00:12
And thatโ€™s why the evil wizard Moldevort is planning to use it
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ื•ื–ื” ืœืžื” ื”ืงื•ืกื ื”ืžืจื•ืฉืข ืžื•ืœื“ื•ื•ืจื˜ ืžืชื›ื ืŸ ืœื”ืฉืชืžืฉ ื‘ื•
00:15
to conquer the world.
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ื‘ืฉื‘ื™ืœ ืœื”ืฉืชืœื˜ ืขืœ ื”ืขื•ืœื.
00:17
You and Drumbledrore have finally discovered its hiding place in this cave.
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ืืชื ื•ื“ืจืžื‘ืœื“ืจื•ืจ ื’ื™ืœื™ืชื ืืช ืžืงื•ื ื”ืžื—ื‘ื•ื ืฉืœื• ื‘ืžืขืจื” ื”ื–ื•.
00:23
The wand is hidden by a system of 100 magical stonesโ€”
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ื”ืฉืจื‘ื™ื˜ ืžื•ืกืชืจ ืขืœ ื™ื“ื™ ืžืขืจื›ืช ืฉืœ 100 ืื‘ื ื™ื ืงืกื•ืžื•ืช,
00:27
including a glowing keystoneโ€” and 100 platforms.
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ื”ื›ื•ืœืœืช ืื‘ืŸ ืžืคืชื— ื–ื•ื”ืจืช, ื•-100 ืคืœื˜ืคื•ืจืžื•ืช.
00:32
If the keystone is placed on the correct platform,
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ืื ืื‘ืŸ ื”ืžืคืชื— ืžื•ื ื—ืช ืขืœ ื”ืคืœื˜ืคื•ืจืžื” ื”ื ื›ื•ื ื”,
00:35
the wand will be revealed.
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ื”ืฉืจื‘ื™ื˜ ื™ืชื’ืœื”.
00:37
If placed incorrectly, the entire cave will collapse.
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ืื ืžื ื™ื—ื™ื ืื•ืชื” ื‘ืฆื•ืจื” ืœื ื ื›ื•ื ื”, ื›ืœ ื”ืžืขืจื” ืชืงืจื•ืก.
00:42
The keystone is immune to all magic, but the other stones aren't,
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ืื‘ืŸ ื”ืžืคืชื— ื—ืกื™ื ื” ื‘ืคื ื™ ื›ืœ ืงืกื, ืื‘ืœ ืฉืืจ ื”ืื‘ื ื™ื ืœื,
00:46
meaning you can pick them up and cast a placement spell,
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ื›ืœื•ืžืจ ืฉืืคืฉืจ ืœื”ืจื™ื ืื•ืชืŸ ื•ืœื”ื˜ื™ืœ ื›ื™ืฉื•ืฃ ืžื™ืงื•ื,
00:49
and the platform that stone belongs on will glow.
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ื•ื”ืคืœื˜ืคื•ืจืžื” ืฉื”ืื‘ืŸ ืฉื™ื™ื›ืช ืืœื™ื™ื” ืชื™ื–ื”ืจ.
00:53
Place all 99 stones correctly
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ื”ื ื™ื—ื• ืืช ื›ืœ 99 ื”ืื‘ื ื™ื ื‘ืฆื•ืจื” ื”ื ื›ื•ื ื”
00:55
and the final platform must be the keystoneโ€™s correct resting place.
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ื•ื”ืคืœื˜ืคื•ืจืžื” ื”ืื—ืจื•ื ื” ื—ื™ื™ื‘ืช ืœื”ื™ื•ืช ื”ืžืงื•ื ื”ื ื›ื•ืŸ ืฉืœ ืื‘ืŸ ื”ืžืคืชื—.
01:00
Youโ€™re about to get started when one of Moldevortโ€™s henchmen arrives
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ืืชื ืขื•ืžื“ื™ื ืœื”ืชื—ื™ืœ ื›ืฉืื—ื“ ืžื”ืžืฉืจืชื™ื ืฉืœ ืžื•ืœื“ื•ื•ืจื˜ ืžื’ื™ืข
01:03
and irreversibly seals a random stone to a random platform.
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ื•ืžืงื‘ืข ื‘ืื•ืคืŸ ื‘ืœืชื™ ื”ืคื™ืš ืื‘ืŸ ืืงืจืื™ืช ืœืคืœื˜ืคื•ืจืžื” ืืงืจืื™ืช.
01:08
If you need to place a stone that belongs on a platform that's already occupied,
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ืื ืชื ืกื• ืœื”ื ื™ื— ืื‘ืŸ ืฉืฉื™ื™ื›ืช ืœืคืœื˜ืคื•ืจืžื” ืฉื›ื‘ืจ ืชืคื•ืกื”,
01:13
your spell will make some random unoccupied platform glow instead.
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ื”ื›ื™ืฉื•ืฃ ืฉืœื›ื ื™ื’ืจื•ื ืœืคืœื˜ืคื•ืจืžื” ืคื ื•ื™ื” ืืงืจืื™ืช ืœื”ืื™ืจ ื‘ืžืงื•ื.
01:19
What are your odds of placing the keystone on the correct platform?
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ืžื” ื”ืกื™ื›ื•ื™ื™ื ืฉืœื›ื ืœืžืงื ืืช ืื‘ืŸ ื”ืžืคืชื— ื‘ืคืœื˜ืคื•ืจืžื” ื”ื ื›ื•ื ื”?
01:24
Pause now to figure it out for yourself. Answer in 3
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[ืขืฆืจื• ืขื›ืฉื™ื• ืื ืชืจืฆื• ืœื ืกื•ืช ืœื’ืœื•ืช ื‘ืขืฆืžื›ื]
01:26
Answer in 2
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ืชืฉื•ื‘ื” ื‘ืขื•ื“ 2
01:28
Answer in 1
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ืชืฉื•ื‘ื” ื‘ืขื•ื“ 1
01:32
Letโ€™s imagine we knew everything about this situation.
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ื‘ื•ืื• ื ื“ืžื™ื™ืŸ ืฉืื ื• ื™ื•ื“ืขื™ื ื”ื›ืœ ืขืœ ื”ืžืฆื‘.
01:35
With perfect knowledge, we could label the stones 1 to 100,
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ืขื ื™ื“ืข ืžื•ืฉืœื, ื ื•ื›ืœ ืœืชื™ื™ื’ ืืช ื”ืื‘ื ื™ื 1 ืขื“ 100,
01:39
based on the order we plan to place them,
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ื‘ื”ืชืื ืœืกื“ืจ ืฉืื ื• ืžืชื›ื ื ื™ื ืœื”ื ื™ื— ืื•ืชืŸ,
01:41
and label the platforms they belong on in the same way.
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ื•ืœืชื™ื™ื’ ืืช ื”ืคืœื˜ืคื•ืจืžื•ืช ืฉื”ืŸ ืฉื™ื™ื›ื•ืช ืืœื™ื”ืŸ ื‘ืื•ืชื• ืื•ืคืŸ.
01:45
Weโ€™ll label the stone the henchmen placed as 1,
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ื ืชื™ื™ื’ ืืช ื”ืื‘ืŸ ืฉื”ืžืฉืจืช ืงื™ื‘ืข ื›-1,
01:48
meaning it was supposed to go on platform 1,
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ืžืฉืžืข ืฉื”ื™ื ื”ื™ื™ืชื” ืืžื•ืจื” ืœื”ื™ื•ืช ืขืœ ืคืœื˜ืคื•ืจืžื” 1,
01:51
and the keystone as 100, belonging on platform 100.
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ื•ืืช ืื‘ืŸ ื”ืžืคืชื— ื›-100, ื‘ืฉื™ื•ืš ืœืคืœื˜ืคื•ืจืžื” 100.
01:56
Of course, we donโ€™t know which platform is which,
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ื›ืžื•ื‘ืŸ, ืื ื—ื ื• ืœื ื™ื•ื“ืขื™ื ืื™ื–ื• ื”ื™ื ืื™ื–ื•,
01:59
so the numbering of the platforms is actually invisible to us.
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ืื– ืžืกืคื•ืจ ื”ืคืœื˜ืคื•ืจืžื•ืช ื”ื•ื ืœืžืขืฉื” ื‘ืœืชื™ ื ืจืื” ืœื ื•.
02:03
There are three possibilities:
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ื™ืฉ ืฉืœื•ืฉ ืืคืฉืจื•ื™ื•ืช:
02:05
one, that first stone was placed randomly onto its own platform,
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ืื—ืช, ื”ืื‘ืŸ ื”ืจืืฉื•ื ื” ื”ื•ื ื—ื” ื‘ืืงืจืื™ ืขืœ ื”ืคืœื˜ืคื•ืจืžื” ืฉืœื”,
02:10
in which case, youโ€™re guaranteed to succeed.
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ื‘ืžืงืจื” ื›ื–ื”, ื”ื”ืฆืœื—ื” ืžื•ื‘ื˜ื—ืช.
02:13
Two, it was placed on the keystoneโ€™s platform and youโ€™re doomed to fail.
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ืฉืชื™ื™ื, ื”ื™ื ื”ื•ื ื—ื” ืขืœ ื”ืคืœื˜ืคื•ืจืžื” ืฉืœ ืื‘ืŸ ื”ืžืคืชื— ื•ืืชื ื ื™ื“ื•ื ื™ื ืœื”ื™ื›ืฉืœ.
02:18
But most likelyโ€” scenario threeโ€” it was placed somewhere else.
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ืื‘ืœ ืกื‘ื™ืจ ื™ื•ืชืจ ื”ืชืจื—ื™ืฉ ื”ืฉืœื™ืฉื™โ€” ื”ื™ื ื”ื•ืฆื‘ื” ื‘ืžืงื•ื ืื—ืจ.
02:23
Suppose the henchman placed stone 1 on, say, platform 45.
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ื ื ื™ื— ืฉื”ืขื•ื–ืจ ืžื™ืงื ืืช ืื‘ืŸ 1 ืขืœ, ืœืžืฉืœ, ืคืœื˜ืคื•ืจืžื” 45.
02:27
Then youโ€™d place stone 2 on platform 2,
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ืื– ืืชื ืชื ื™ื—ื• ืืช ืื‘ืŸ 2 ืขืœ ืคืœื˜ืคื•ืจืžื” 2,
02:31
3 on 3, and so on, until you got to stone 45.
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3 ืขืœ 3, ื•ื›ื•ืœื™, ืขื“ ืฉืชื’ื™ืขื• ืœืื‘ืŸ 45.
02:35
Its platform being taken, a random platform would light up.
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ืžื›ื™ื•ื•ืŸ ืฉืžืงื•ืžื” ืชืคื•ืก, ืคืœื˜ืคื•ืจืžื” ืืงืจืื™ืช ืชื™ื“ืœืง.
02:39
And here, there are three possibilities:
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ื•ื›ืืŸ ื™ืฉ ืฉืœื•ืฉ ืืคืฉืจื•ื™ื•ืช:
02:42
If itโ€™s platform 1, youโ€™ll win,
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ืื ื–ืืช ืคืœื˜ืคื•ืจืžื” 1, ืืชื ืชื ืฆื—ื•,
02:44
because all of the remaining stones will go to the correct platforms.
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ื‘ื’ืœืœ ืฉื›ืœ ืฉืืจ ื”ืื‘ื ื™ื ื™ื•ื ื—ื• ืขืœ ื”ืคืœื˜ืคื•ืจืžื•ืช ื”ื ื›ื•ื ื•ืช.
02:48
If platform 100 lights up, you lose,
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ืื ืคืœื˜ืคื•ืจืžื” 100 ืชื™ื“ืœืง, ืชืคืกื™ื“ื•,
02:51
because the keystoneโ€™s spot will be taken.
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ื‘ื’ืœืœ ืฉืžืงื•ืžื” ืฉืœ ืื‘ืŸ ื”ืžืคืชื— ื™ื™ืชืคืก.
02:54
Any other platform, and youโ€™re essentially back where you started,
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ื›ืœ ืคืœื˜ืคื•ืจืžื” ืื—ืจืช, ื•ืืชื ื‘ืขืฆื ืชื—ื–ืจื• ืœืื™ืคื” ืฉื”ืชื—ืœืชื,
02:57
just with 54 remaining stones and one on the wrong platform.
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ืจืง ืขื 54 ืื‘ื ื™ื ื ื•ืชืจื•ืช, ื•ืื—ืช ืขืœ ืคืœื˜ืคื•ืจืžื” ืฉื’ื•ื™ื”.
03:02
In that scenario, letโ€™s say the spell tells us to place stone 45 on platform 82.
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ื‘ืชืจื—ื™ืฉ ื”ื–ื”, ื ื ื™ื— ืฉื”ื›ื™ืฉื•ืฃ ืžืจืื” ืœื ื• ืœืฉื™ื ืืช ืื‘ืŸ 45 ืขืœ ืคืœื˜ืคื•ืจืžื” 82.
03:08
Then we place 46 to 81 correctly, and 82 at random.
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ืื– ื ื ื™ื— ืืช 46 ืขื“ 81 ื‘ืฆื•ืจื” ื ื›ื•ื ื”, ื•ืืช 82 ื‘ืืงืจืื™ื•ืช.
03:13
And here we reach the same three possibilities:
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ื•ื›ืืŸ ืื ื—ื ื• ืžื’ื™ืขื™ื ืœืื•ืชืŸ ืฉืœื•ืฉ ืืคืฉืจื•ื™ื•ืช:
03:16
pedestal 1, you win, pedestal 100, you lose,
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ืžืขืžื“ 1, ื ื™ืฆื—ืชื, ืžืขืžื“ 100, ื”ืคืกื“ืชื,
03:20
any other, you continue the process.
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ื›ืœ ืื—ื“ ืื—ืจ, ื•ืืชื ืžืžืฉื™ื›ื™ื ื‘ืชื”ืœื™ืš.
03:23
In other words, youโ€™re playing a game where you have equal chances
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ื‘ืžื™ืœื™ื ืื—ืจื•ืช, ืืชื ืžืฉื—ืงื™ื ื‘ืžืฉื—ืง ืฉื‘ื• ื™ืฉ ืœื›ื ืกื™ื›ื•ื™ื™ื ืฉื•ื•ื™ื
03:27
to win and lose,
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ืœื ืฆื— ื•ืœื”ืคืกื™ื“,
03:28
and some chance to delay the decisive moment.
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ืขื ืกื™ื›ื•ื™ ืœื“ื—ื•ืช ืืช ื”ืจื’ืข ื”ืžื›ืจื™ืข.
03:32
No matter how many times this process repeats,
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ืœื ืžืฉื ื” ื›ืžื” ืคืขืžื™ื ื”ืชื”ืœื™ืš ื”ื–ื” ื—ื•ื–ืจ ืขืœ ืขืฆืžื•,
03:35
youโ€™ll inevitably either place a stone on pedestal 1 or pedestal 100
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ื‘ื”ื›ืจื— ืชื ื™ื—ื• ืื‘ืŸ ืขืœ ืžืขืžื“ 1 ืื• ืžืขืžื“ 100
03:40
before you reach the keystone.
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ืœืคื ื™ ืฉืชื’ื™ืขื• ืœืื‘ืŸ ื”ืžืคืชื—.
03:42
Thatโ€™s all that determines whether you succeed or fail,
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ื–ื” ื›ืœ ืžื” ืฉืงื•ื‘ืข ืื ืชืฆืœื™ื—ื• ืื• ืชื™ื›ืฉืœื•,
03:45
and critically, the chances of those events are equal.
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ื•ื‘ืื•ืคืŸ ืงืจื™ื˜ื™, ื”ืกื™ื›ื•ื™ื™ื ืœืื™ืจื•ืขื™ื ืืœื” ืฉื•ื•ื™ื.
03:49
This can be unintuitive, so letโ€™s imagine another, similar game.
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ื–ื” ื™ื›ื•ืœ ืœื”ื™ื•ืช ืœื ืื™ื ื˜ื•ืื™ื˜ื™ื‘ื™, ืื– ื‘ื•ืื• ื ื“ืžื™ื™ืŸ ืžืฉื—ืง ืื—ืจ, ื“ื•ืžื”.
03:53
Say Drumbledrore magically generates numbers from 1 to 100.
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ื ื’ื™ื“ ืฉื“ืจืžื‘ืœื“ืจื•ืจ ืžื™ื™ืฆืจ ื‘ืฆื•ืจื” ืงืกื•ืžื” ืžืกืคืจื™ื ืž-1 ืขื“ 100.
03:57
If itโ€™s a 1, you win.
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ืื ื–ื” 1, ื ื™ืฆื—ืชื.
03:59
If itโ€™s 100, you lose.
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ืื ื–ื” 100, ื”ืคืกื“ืชื.
04:01
If itโ€™s anything else, he picks again.
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ืื ื–ื” ื›ืœ ืžืกืคืจ ืื—ืจ, ื”ื•ื ื‘ื•ื—ืจ ืฉื•ื‘.
04:04
Since the odds of winning by getting 1 are the same as losing by getting a 100,
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ืžื›ื™ื•ื•ืŸ ืฉื”ืกื™ื›ื•ื™ื™ื ืœื ืฆื— ืขืœ ื™ื“ื™ ืงื‘ืœืช 1 ื–ื”ื™ื ืœื”ืคืกื“ ืขืœ ื™ื“ื™ ืงื‘ืœืช 100,
04:09
this is a game youโ€™re just as likely to win as to lose.
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ื–ื”ื• ืžืฉื—ืง ืฉื‘ื• ื”ืกื™ื›ื•ื™ ืœื ืฆื— ืฉื•ื•ื” ืœืกื™ื›ื•ื™ ืœื”ืคืกื™ื“
04:13
It might take a while, but the delays donโ€™t give an advantage
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ื–ื” ืขืฉื•ื™ ืœืงื—ืช ื–ืžืŸ, ืื‘ืœ ื”ืขื™ื›ื•ื‘ื™ื ืœื ื ื•ืชื ื™ื ื™ืชืจื•ืŸ
04:16
to getting a 1 before 100, or vice versa.
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ื›ื“ื™ ืœืงื‘ืœ 1 ืœืคื ื™ 100, ืื• ืœื”ื™ืคืš.
04:19
The same essential reasoning applies to our situation.
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ืื•ืชื• ื ื™ืžื•ืง ืžื”ื•ืชื™ ื—ืœ ืขืœ ืžืฆื‘ื ื•.
04:23
Youโ€™re debating whether itโ€™s worth risking a 50/50 chance of a cave-in
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ืืชื ืžืชืœื‘ื˜ื™ื ืื ื›ื“ืื™ ืœืงื—ืช ืกื™ื›ื•ืŸ ืฉืœ 50/50 ืœื”ืชืžื•ื˜ื˜ื•ืช
04:28
when Drumbledrore reveals his secret weapon:
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ื›ืฉื“ืจืžื‘ืœื“ืจื•ืจ ื—ื•ืฉืฃ ืืช ื ืฉืงื• ื”ืกื•ื“ื™:
04:31
a rare felush felucious potion,
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ืฉื™ืงื•ื™ โ€œืคืœื•ืฉ ืคืœื•ืฉื™ื•ืกโ€ ื ื“ื™ืจ
04:34
which grants extraordinary luck for a brief period of time.
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ืฉืžืขื ื™ืง ืžื–ืœ ื™ื•ืฆื ื“ื•ืคืŸ ืœืคืจืง ื–ืžืŸ ืงืฆืจ.
04:38
Thereโ€™s a 1 in 100 chance the keystoneโ€™s platform was taken
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ื™ืฉ ืกื™ื›ื•ื™ ืฉืœ 1 ืœ-100 ืฉื”ืคืœื˜ืคื•ืจืžื” ืฉืœ ืื‘ืŸ ื”ืžืคืชื— ื ืชืคืกื”
04:42
by the first stone and youโ€™ve lost already,
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ืขืœ ื™ื“ื™ ื”ืื‘ืŸ ื”ืจืืฉื•ื ื” ื•ืฉื›ื‘ืจ ื”ืคืกื“ืชื,
04:45
but otherwise, youโ€™ve got even odds to win or lose.
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ืื—ืจืช, ื™ืฉ ืœื›ื ืกื™ื›ื•ื™ื™ื ื–ื”ื™ื ืœื ืฆื— ืื• ืœื”ืคืกื™ื“.
04:49
And right now, youโ€™re feeling lucky.
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ื•ื›ืจื’ืข, ืืชื ืžืจื’ื™ืฉื™ื ื‘ืจื™ ืžื–ืœ.
ืขืœ ืืชืจ ื–ื”

ืืชืจ ื–ื” ื™ืฆื™ื’ ื‘ืคื ื™ื›ื ืกืจื˜ื•ื ื™ YouTube ื”ืžื•ืขื™ืœื™ื ืœืœื™ืžื•ื“ ืื ื’ืœื™ืช. ืชื•ื›ืœื• ืœืจืื•ืช ืฉื™ืขื•ืจื™ ืื ื’ืœื™ืช ื”ืžื•ืขื‘ืจื™ื ืขืœ ื™ื“ื™ ืžื•ืจื™ื ืžื”ืฉื•ืจื” ื”ืจืืฉื•ื ื” ืžืจื—ื‘ื™ ื”ืขื•ืœื. ืœื—ืฅ ืคืขืžื™ื™ื ืขืœ ื”ื›ืชื•ื‘ื™ื•ืช ื‘ืื ื’ืœื™ืช ื”ืžื•ืฆื’ื•ืช ื‘ื›ืœ ื“ืฃ ื•ื™ื“ืื• ื›ื“ื™ ืœื”ืคืขื™ืœ ืืช ื”ืกืจื˜ื•ืŸ ืžืฉื. ื”ื›ืชื•ื‘ื™ื•ืช ื’ื•ืœืœื•ืช ื‘ืกื ื›ืจื•ืŸ ืขื ื”ืคืขืœืช ื”ื•ื•ื™ื“ืื•. ืื ื™ืฉ ืœืš ื”ืขืจื•ืช ืื• ื‘ืงืฉื•ืช, ืื ื ืฆื•ืจ ืื™ืชื ื• ืงืฉืจ ื‘ืืžืฆืขื•ืช ื˜ื•ืคืก ื™ืฆื™ืจืช ืงืฉืจ ื–ื”.

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