Comtuter and Internet News Channel
In social networks, the task that the nine-year-old student asked at home was popular. A photo from the textbook was published on the Mumsnet forum.
Many adults, despite the simplicity of the condition, could not solve the problem.
Here’s how the condition looks: "On the shore there are three lighthouses. The first turns on for three seconds, then turns off for three seconds. The second turns on for four seconds and then turns off for four seconds. The third turns on for five seconds, then turns off for five seconds. All three lighthouses begin to work simultaneously. At what point in time will all three beacons be turned off at the same time? At what point in time will all three beacons turn on at the same time?"
Many parents, noted in the comments, admitted that the task put them at a dead end. At the same time, there were those who could cope with it. The easiest way, as it turned out, is to do this with the help of diagrams.