the most infamous bank robbers in the west.

成為西方最聲名狼藉的銀行搶匪。

Now, you'll need to use that timing to help you break out of jail.

現在你得用這掌控時間的能力 來幫助你逃獄。

At the appointed time, you'll be walking in the yard near the electric fence.

在指定的時間，你會在 通電柵欄附近的院子散步。

Your partner will flash you the signal,

你的夥伴會向你打閃燈信號，

and exactly 45 seconds later,

信號發出後四十五秒，

short out the fence circuit.

就會讓柵欄電路短路。

It'll automatically restart after a second or two,

在一秒或兩秒之後， 它會自動重新啟動，

but as long as you move fast,

但只要你的動作夠快，

you'll be home free.

你就能自由返家。

And then you notice,

接著，你注意到 一件讓你害怕的事，

to your horror,

你的手錶壞了，

that your watch is broken,

且來不及修好它。

and there's no time to fix it.

信號就要來了，

The signal is coming,

如果你在計算四十五秒時 有一點點的誤差，

and if you make even a small mistake in counting off 45 seconds,

你就會燒焦。

you'll get fried.

你在口袋中摸索， 找到了可能可以幫上忙的東西：

Searching your pockets,

一個打火機和兩根保險絲， 是你先前在監獄工作計畫中做的。

you find something that might help:

每一根保險絲都是 一段可燃的線段，

a lighter and two fuses you made earlier in the prison work program.

設計是兩端都可以燃燒，

Each fuse is a length of flammable twine,

剛剛好一分鐘燒盡。

built to be lit on either end and burn for precisely one minute.

問題是雖然保險絲看起來粗細均勻，

The problem is that even though the fuses look uniform,

它們的燃燒並不平均，

they don't burn evenly,

因此如果你把一根保險絲對半切，

so if you cut one in half, for example,

一半的燃燒時間可能會比另一半長。

one side might burn longer than the other.

你的夥伴隨時都會給你信號，

Your partner is going to give the signal any minute,

到時你就得要行動。

and you'll have to make your move.

你要如何用保險絲和打火機 來計時，算出剛好四十五秒？

How can you use the fuses and lighter to time exactly 45 seconds?

如果想嘗試自己解題， 請在此暫停。

Pause the video to figure it out yourself.

答案即將公佈：3

Answer in 3

答案即將公佈：2

Answer in 2

答案即將公佈：1

Answer in 1

保險絲的長度可能 無法給你任何資訊，

The length of the fuse may not tell you anything,

但你確實知道從一端燃燒到 另一端會花剛好六十秒。

but you do know the fuses take exactly 60 seconds to burn from end to end.

關鍵的洞察如下：

Here's the key insight:

如果你從一端點燃一根保險絲， 它燃燒了三十秒，

If you start a fuse on one side and it burns for 30 seconds,

就還有三十秒的保險絲未燃燒。

there'll still be 30 seconds of fuse left.

如果你從另一端開始點燃，

If you had started it from the other end,

在三十秒時， 它也會燒到同一個點。

it would've reached the exact same spot in thirty seconds.

那就表示，如果 你同時從兩端點燃，

That means that if you lit it from both ends simultaneously,

那根保檢絲就會在 剛好三十秒時燒完。

it would burn out in precisely 30 seconds.

但你要如何計算剩下的十五秒？

But how will you time the last fifteen?

那就要用到第二根保險絲了。

That'll have to come from the second fuse.

如果它是一根三十秒的保險絲，

If it were a 30 second fuse,

你就可以故技重施，

you'd be able to use that same trick again

讓燃燒速度變成兩倍， 在十五秒時讓它燒盡。

to double the burning speed and make it last exactly 15 seconds.

你知道，你可以 把第二根保險絲縮短，

And, you realize, you can shorten the second fuse

只要在你點燃第一根保險絲時 同時點燃第二根的一端即可。

by lighting one end of it at the same time as you light the first.

在第一根保險絲燒盡時，

At the moment the first burns out,

你的第二根保險絲就會 剩下剛好三十秒的長度。

you'll be left with 30 seconds on the second fuse.

就在你把這一切都想通之際，

Just when you've got this all figured out,

你看到你的夥伴向你 打信號，立刻採取行動。

you see the signal from your partner,

你把兩根保險絲的四端 集合在一起，點燃其中三端。

and spring into action.

在第一根保險絲燒盡時，

You gather the four ends of the two fuses and light three of them.

你立刻把第二根保險絲的 另一端也點燃。

The moment the first burns out,

當火光搖曳，最後消失，

you light the other end of the second fuse.

你就知道四十五秒過去了，

When it flickers and dies,

通電的柵欄現在停止運作了。

you know that exactly 45 seconds have passed,

在它重新恢復供電時，

and the electric fence is dead.

你已經越過柵欄， 自由自在地返家。

By the time it hiccups back to life,

you're over the fence and home free.