Can you solve the wizard standoff riddle? - Dan Finkel

13,336,069 views ・ 2018-05-22

TED-Ed


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譯者: Lilian Chiu 審譯者: Helen Chang
00:07
You’ve been chosen as a champion to represent your wizarding house
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你被選為你的巫術學院的代表
00:11
in a deadly duel against two rival magic schools.
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與兩間魔法學校的對手致命決鬥。
00:15
Your opponents are fearsome.
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你的對手讓人望而生畏。
00:17
From the Newt-niz school,
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來自 Newt-niz 學校,
00:18
a powerful sorcerer wields a wand that can turn people into fish,
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是一個強大的法師, 他揮動魔杖就能把人變成魚,
00:23
but his spell only works 70% of the time.
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但他的咒語只有 70% 的成功率。
00:27
And from the Leib-ton school,
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另外還有來自 Leib-ton 學校,
00:29
an even more powerful enchantress wields a wand that turns people to statues,
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是位更強大的女巫, 揮動魔杖就能把人變成雕像,
00:34
and it works 90% of the time.
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且成功率有 90%。
00:37
Lots are drawn, and you’re chosen to cast the first spell in the duel.
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抽籤的結果是,你被抽中 在決鬥中可以先施魔咒。
00:42
The Newt-niz magician will go second,
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Newt-niz 的魔法師排在第二,
00:44
and the Leib-ton enchantress third,
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Leib-ton 的女巫則是第三,
00:47
after which you’ll repeat casting in that order until only one of you is left.
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之後,就用這個順序輪流施魔咒, 直到只剩下一人為止。
00:53
The rules of magic duels are strict,
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魔法決鬥的規則很嚴格,
00:55
and anyone who casts out of order immediately forfeits the duel.
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不照順序施魔咒的人 就馬上喪失決鬥資格。
01:00
Also, to prevent draws,
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此外,為了避免平手,
01:01
the rules stipulate that if everyone’s still standing
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規則規定,只要在第一回合的最後
01:04
at the end of the first round,
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所有人都沒倒下,
01:06
you’ll all be turned into cats.
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所有人都會被變為貓。
01:09
Now, you must choose a wand.
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現在,你必須選擇一枝魔杖。
01:11
Your wizarding house presents you with three options:
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你的巫術學院提供你三個選擇:
01:14
the Bannekar, which binds one target with vines
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Bannekar,能將一個目標 用藤蔓綁住,
01:18
and casts effectively 60% of the time,
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成功率為 60%,
01:21
the Gaussian, which turns one target into a tree
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Gaussian,能將一個目標 變成一棵樹,
01:25
and works 80% of the time,
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成功率為 80%,
01:27
and the incredibly rare Noether 9000,
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還有非常稀有的 Noether 9000,
01:30
which banishes one target to a distant mountaintop
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能將一個目標流放到 遙遠的山頂上,
01:33
and casts perfectly 100% of the time.
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成功率是完美的 100%。
01:37
Your opponents are masters of strategy, as well as sorcery,
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你的對手精通策略以及法術,
01:41
and you know they’ll make the choices that maximize their own chances of success.
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你知道他們做選擇的考量是要 讓他們自己的成功率能達到最高。
01:46
Which wand should you choose
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你該選擇哪一枝魔杖
01:48
and what strategy should you employ
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且要採取哪一種策略
01:50
to have the greatest chance of winning the duel?
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才最有可能贏得決鬥?
01:53
Pause the video now if you want to figure it out for yourself!
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如果你想要自己解解看, 在這裡將影片暫停!
01:56
Answer in: 3
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公佈答案倒數:三。
01:57
Answer in: 2
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公佈答案倒數:二。
01:59
Answer in: 1
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公佈答案倒數:一。
02:00
You reach for the Noether 9000 first.
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你一開始想要拿 Noether 9000。
02:03
After all, it makes sense to enter the duel with the most powerful wand.
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畢竟,帶著最強大的魔杖 參加決鬥是合理的選擇。
02:07
But before you pick it up, you consider what would happen.
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但,在你把它拿起來之前, 你想了一下會發生的狀況。
02:11
As the most dangerous wizard,
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若你是決鬥中最危險的巫師,
02:13
you’d also be the target of the other two magicians,
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你就會成為另外 兩位魔法師的目標,
02:16
and you’d need to take care of the most dangerous of them first.
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而你得要先把他們兩人當中 最危險的那一位解決掉。
02:20
But afterward, there’s a 70% chance you'd be struck down by the remaining wizard.
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但,之後,就有 70% 的可能, 你會被剩下的那位巫師擊倒。
02:25
That’s trouble.
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那就是問題所在。
02:27
Maybe it’s better to take the Gaussian.
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也許選 Gaussian 會比較好。
02:29
It works 80% of the time,
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它的成功率有 80%,
02:31
which means you wouldn’t be a target until the enchantress was incapacitated.
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那就表示,在女巫被打倒之前, 你都不會成為目標。
02:36
But if you succeeded in transforming her,
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但如果你成功將她變身,
02:39
you’d probably be turned into a fish immediately after.
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你可能接著馬上就會被變成魚。
02:42
If you transformed the sorcerer,
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如果你把法師變身,
02:44
the enchantress would almost certainly turn you to stone.
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幾乎可肯定女巫會把你變成石頭。
02:48
It would really be better if you missed.
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如果你失誤反而會更好。
02:51
And that’s when you have an idea:
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此時,你就有了個點子:
02:53
what if you took the Gaussian, then missed on purpose?
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如果你選擇 Gaussian, 然後故意失誤呢?
02:57
Then, you would wait for the sorcerer to attack the enchantress,
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那麼,你就可以等法師攻擊女巫,
03:00
and you’d have an 80% chance of winning against the sorcerer.
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且你會有 80% 的機會打贏法師。
03:04
It’s a good idea, but there’s a problem;
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這是個好點子,但有個問題:
03:07
the sorcerer could also pass his turn
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法師也有可能故意失誤,
03:10
and the enchantress, knowing that she couldn’t pass without becoming a cat,
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那麼女巫知道她不能在不被 變成貓的情況下通過第一回合,
03:14
would cast her spell on one of you.
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她就會對你或法師 其中一人施魔咒。
03:17
And since you’re the most dangerous between you and the sorcerer,
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因為和法師相比,你比較危險,
03:21
you’d be the target.
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你就會成為目標。
03:22
And that’s when you see what you really need to do:
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此時,你就知道 你真正該做什麼選擇了:
03:25
take the weakest wand, the Bannekar, and miss on purpose.
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拿最弱的魔杖 Bannekar, 並且故意失誤。
03:29
Now the sorcerer knows that he’ll be targeted by the enchantress
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現在,法師知道 他會成為女巫的目標,
03:32
and he’ll have to try to turn her into a fish to avoid being turned into stone.
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他就會試著將女巫變成魚, 來避免自己被變成石頭。
03:37
Seventy percent of the time he’d succeed
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他的成功機會有 70%,
03:40
and you’d have a 60% chance of winning the duel
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而在下一回點開始時,
03:43
at the beginning of the next round.
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你有 60% 的機會贏得決鬥。
03:45
If he fails, chances are he’ll be turned to stone
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如果他失敗了, 他很可能會被變成石頭,
03:48
and you’d still have a 60% chance of winning the duel against the enchantress.
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而你要和女巫決鬥, 會有 60% 的機會獲勝。
03:53
There’s a slim 3% chance you’ll all be turned into cats,
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只有 3% 非常低的可能性, 所有人會被變成貓。
03:57
but when everything’s accounted for,
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但把一切都考量進去後,
03:59
you have better than even odds of winning with this strategy.
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用這個策略你會有最高的勝算。
04:03
And that’s the best you can do.
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這是你能做到最好的狀況。
04:05
Here’s what the probability of winning for the different strategies looks like.
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表中列出的是 不同策略的獲勝機率。
04:11
Who would’ve thought that the best way to take your shot
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誰想得到,最好的攻擊方式,
04:14
would be to throw away your shot?
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就是放棄自己的攻擊機會?
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