Can you solve the secret sauce riddle? - Alex Gendler

3,308,906 views ・ 2019-09-16

TED-Ed


请双击下面的英文字幕来播放视频。

翻译人员: Carol Wang 校对人员: Heze Ma
00:07
One of the top chefs from Pasta Palace
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意粉宫餐厅的顶级厨师之一
00:10
has been kidnapped by operatives from Burger Bazaar
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被汉堡殿餐厅工作人员绑架,
00:13
hoping to learn the location of their secret sauce recipe.
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他们想获知其秘制酱汁配方藏在哪里。
00:18
Little do they know that a third party—
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他们有所不知,
第三方餐厅热狗城
00:20
Sausage Saloon—
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00:21
has sent you to take advantage of the situation.
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也派他们的最高间谍, 也就是你,前来打探。
00:25
As their top spy, your skills range from infiltration and subterfuge,
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作为他们的顶级间谍,
你精通卧底、诡计、 开保险箱和读心术。
00:29
to safecracking and reading faces for signs of deception.
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00:33
You’ve tracked the captors to where they’re holding the chef prisoner.
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你跟踪到他们关押厨师的地方,
00:38
From your hiding spot, you can see him on the other side of the glass,
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从你的藏身之处, 能看到玻璃另一边的厨师,
00:42
while in front of you an interrogator wearing headphones
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而在你的面前,
戴耳机的审讯者正对着麦克风说话。
00:45
speaks into a microphone.
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00:47
“We already know the recipe is on the 13th floor of the bank vault,
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“我们得知配方在银行金库 13 楼,
00:50
in a safe deposit box numbered between 13 and 1300.
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在编号 13 到 1300 间的保险箱里。
00:54
Now tell us… Is the number less than 500?”
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现在告诉我们, 这个数字小于 500 吗?”
00:59
You can’t hear the chef’s answer, but you can see that he’s lying.
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你听不到厨师的回答, 但你可以看出他在撒谎,
01:02
The interrogator, however, falls for it.
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但审讯者相信了厨师的话。
01:06
He follows up by asking, “Is it a perfect square?”
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他接着问道: “这个数是完全平方吗?”
01:09
Again you can’t hear the answer but can tell the chef is lying,
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你听不见答案, 但能看出厨师又撒谎了,
01:14
while the interrogator takes him at his word.
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而审讯者相信了他的话。
01:16
He then asks, “Is it a perfect cube?”
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然后他问:“它是完全立方吗?”
01:19
This time the chef answers truthfully.
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这一次,厨师如实回答了。
01:23
The interrogator thinks for a minute and says,
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审讯者想了一会儿,说道:
01:25
“Good. Now if you just tell me whether or not the number’s second digit is a one,
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“好。 现在只要你告诉我 第二位数字是不是 1 ,
01:29
we’ll be done here.”
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你就没事了。”
01:31
But as the chef starts to answer,
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但当厨师开始回答时,
01:33
the interrogator stands up, blocking your view.
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审讯者站起来,挡住了你的视线。
01:37
Within moments he rushes out of the room,
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不一会儿,他就冲出了房间,
01:39
announcing that he’s got the answer and is sending agents to retrieve the recipe.
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宣布他得到了答案,并派人去取配方。
01:44
You know that the Burger Bazaar people have the wrong box number.
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你知道汉堡殿餐厅的人 得到的箱号是错的,
01:48
But can you figure out the right one and retrieve the recipe yourself?
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但你能想出正确的号码 并拿到配方吗?
01:52
Pause the video to figure it out for yourself.
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[ 若想自己解题,请暂停播放 ]
01:54
Answer in 3
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[ 答案公布:3 ]
01:55
Answer in 2
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[ 答案公布:2 ]
01:58
Answer in 1
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[ 答案公布:1 ]
02:00
The key here is to work backwards.
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解题的关键是倒推。
02:03
We don’t know what the chef answers to the final question
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我们不知道最后问题的回答,
02:06
or whether he answers truthfully.
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以及厨师是否撒谎了,
02:08
But we do know that by the time the interrogator asks it,
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但我们确实知道,当审讯者提问时,
02:11
he’s narrowed the options down to two numbers–
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他将范围缩小到两个数——
02:14
one where the second digit is 1, and one where it isn’t.
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一个数的第二位为 1,而另一个不是。
02:18
Our goal, then, is to find answers to the previous questions
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那么,我们的目标
是找出导致仅 2 个数的 先前问题的答案。
02:22
that lead to just two possibilities.
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02:25
Of the three constraints offered,
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在提问的三个问题中,
02:26
the one that narrows our options the most is if the number is a perfect cube.
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最能缩小我们选项的, 是该数是否为完全立方,
02:31
That leaves us with only eight answers between 13 and 1300.
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而 13 到 1300 之间 只有 8 个数符合要求。
02:36
So let’s assume the answer to the third question was a truthful YES.
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假设第三个问题的答案是真的,
02:41
Now, let’s look at the second question.
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接着看第二个问题。
02:43
If the chef answered YES to the number being a perfect square,
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如果厨师回答说它是完全平方,
02:46
it would narrow the interrogator’s options to just 64 and 729–
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那么审讯者的选项 缩小为 64 和 729——
02:52
the only numbers in our range that are both a square and a cube.
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只有这两个数 同时是完全平方完全立方。
02:57
But neither of these has a 1 as the second digit.
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但这两个数的第二位都不是 1,
03:00
So the given answer to the second question must’ve been NO.
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所以,第二个问题的答案 肯定是否定的,
03:04
And that also means we can eliminate these two squares from the interrogator's list,
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也就是说,可以把这两个数 从审讯者的选项中删掉,
03:09
leaving only six numbers.
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这样,只剩下六个数字。
03:12
Now for the first question, which allows us to divide this list.
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现在回到第一个问题, 可以把候选答案一分为二。
03:16
If the chef answered YES to the number being less than 500,
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数字是否小于 500 的问题, 如果厨师回答“是”,
03:20
we’d have four options, which is too many.
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我们有四个选项,太多了。
03:22
But a NO leaves us with two numbers greater than 500,
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若厨师的回答是“否”的话, 则只有两个数字大于 500,
03:26
one of which does have a 1 as its second digit.
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其中一个数的第二位是 1。
03:30
We don’t know which of these numbers the interrogator thinks is correct.
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我们不知道审讯者选了哪个数,
03:34
But that doesn’t matter–
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但没关系——
03:35
remember, his conclusion was based on lies.
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记住,他的结论是基于谎言得出的,
03:38
You, on the other hand, are now in a position to reconstruct the truth.
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也就是说,你现在可以得出正确结论。
03:44
First, the chef said the number was greater than 500 but lied,
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首先,厨师谎称数字大于 500,
03:48
meaning it’s actually less than 500.
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这意味着它实际上小于 500;
03:51
Second, the chef said it wasn’t a perfect square but lied again,
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其次,厨师谎称它不是完全平方,
03:56
meaning the number is indeed a square.
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而实际上它是完全平方;
03:59
And finally, he truthfully confirmed that it was also a cube.
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最后,他承认它完全立方。
04:03
And as we’ve already seen,
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正如我们已经看到的那样,
04:04
the only number under 500 that’s both a square and a cube is 64.
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小于 500 的数中,只有 64 同时完全平方和完全立方。
04:10
You find the secret recipe and are gone before anyone’s the wiser.
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在其他人弄明白前, 你成功拿到秘方后离开了。
04:15
Corporate espionage is not an easy game—
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企业间谍活动并非易事 ——
04:17
but sometimes, that’s just how the sausage is made.
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但有时,就是仅为得到香肠配方。
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