【轻阅读，看世界】What is a brain teaser that is very short and extremely hard for adults?

Some of you might be familiar with Amazon’s interview problem.

At some point, competitors were given problems as part of the interview.

This problem was given to future employees at Jeff Bezos’s company, bright people with degrees in math, physics, chemistry, engineering and so on.

(what is the length between the two poles if the hanging cable is 80m long, poles are 50m tall and the distance between the hanging cable and the ground is 10m?)

A piece of cake for people with degrees in math, don’t you think?

Well they started solving it straight away using tangent equations, hyperbolic functions and trigonometry.

But they all got stuck at a certain point — all of them ended up with an equation like this:

(40 + a)²/a² – (40/a)²= 1

Then their brains froze to death.

This equation has no possible solutions.

Most competitors failed; this was a timed question and they wasted their time finding the right equations just to get to a point where the problem is stuck.

Before I tell you how simply you can solve this, here’s my personal experience.

I showed this problem to my colleagues, they all tried to solve it because it sounds very interesting. We had a French class and literally everyone was busy struggling to solve the problem, getting angry and throwing away their papers.

They submitted some answers like 6 meters, 1 meter, one even told me it was 8 meters, I replied to all of them: NO.

Then I went to my math and physics teachers; they spent a whole hour trying but they eventually abandoned it. A MATH teacher failed. That surprised me a lot.

Give it a quick try right now before scrolling.

Here is what they got wrong:

Half of the cable is 40 meters long (80/2=40).

Now, notice that the pole is 50 meters tall, but the distance from the cable to the ground is 10 meters! This means that the pole is 40 meters above the cable.

If you think about it, the cable is then hanging directly downward! The whole cable is packed tight between the two poles and the distance between them is ZERO!

Amazed? This was a simple thinking problem, only basic math was needed.

Turns out Amazon wants people that think first, then go into solving problems, critical thinking was more valuable than trigonometry or any equation this time.