Only 10% of People Can Solve This Bridge Math Problem

All that's needed is a little trip down the memory lane, remember the Pythagoras Theorem from high school?
Fabienne Lang
The bridge, the man, the problem.Yours Logically/YouTube

School math problems either bring up dread or excitement. Regardless of which feeling is evoked, even fully functioning adults who have long left behind school arithmetics and geometry struggle to answer simple math questions. 

One such question, or problem, is making the rounds on the Internet, making you wish you'd paid more attention during school.

It's believed roughly 90% of people fail at figuring this bridge problem out, so YouTuber Logically Yours took it upon himself to solve it — in under four minutes — for all to see. 

Watch and learn. 


In typical mathematical language, the puzzle starts as follows "There is a bridge that is 4,000 miles (6,437 km) long from beginning to end. The bridge has a handrail for pedestrians. During summer, the metal used in the handrail slightly expands by one inch. Imagine the handrail’s end points are fixed, which means when it expands, it buckles up at its exact center point.

Yes, 4,000 miles is one heck of a long bridge, but since when did school math problems make much sense? Remember all the fruit-related math questions? Point made. 

So back to the problem at hand, it reads on, "A pedestrian is standing at the center of the bridge in summer. Is it possible for the person to touch the center of the handrail and confidently say if the handrail has expanded?"

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Ok so it's safe to say that the answer should be a resounding yes, but think again. 

Your trusty but long-forgotten friend, the Pythagoras Theorum, has to make an appearance in this puzzle. In the YouTube explanatory video, Logically Yours explains that the height of the couterpoint when buckled needs to be figured out — he breaks it down for all below: 

Only 10% of People Can Solve This Bridge Math Problem
Hello Pythagoras theory my old friend. Source: Yours Logically/YouTube

Watch the video to find out the exact details, but it'll be clear to see the person can't touch the center of the handrail, as it's 938 feet (11,257 inches) up in the air. 

This may sound like a ridiculous question to pose, but there is a correlation to real-life engineering — as math questions tend to do. For instance, Men's Health points out that train track constrution uses such a problem. In the summertime, train track metal can expand and cause them to buckle if this expansion isn't taken into account. This is why they have little gaps between the bolts. 

Go, math!

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