Some riddles are more than just a bit of fun — they're also an effective intelligence barometer. The following brain-teaser from TED-Ed will test both your maths knowledge and ability to think outside the box. It starts with four people who need to get to the other side of a bridge, each with their own walking speeds and quickly gets complicated...
Got your pen and paper ready? Here is the setup:
Four people need to get to the other side of a bridge in 17 minutes before it collapses. Person A can get across in one minute, Person B in two minutes, Person C in five, and Person D, who presumably has no legs, takes ten. The bridge can only support two of them for each trip (the person with the longer time is counted when travelling in a pair). To complicate matters further, it’s dark and the party only has one torch — so a person who has crossed the bridge has to come back for a return trip in order to lead another person across. How do you get everybody across in 17 minutes?
The below video contains the full solution. Let us know how you went in the comments!