There are three lighthouses on three neighbouring islands. The first one flashes its light for 3 seconds, then turns it off for 3 seconds. The second light is on for 4 seconds and then off for 4 seconds. The third light is on for 5 seconds and then off for 5 seconds. All of the lights have just switched on at the same time; when is the next time they will all switch on at the same time?
The times between the lights switching on are 6, 8 and 10 seconds, and the lowest common multiple is 120 (2*5*4*3).
This was set as a maths problem for a year 4 class, and required much head scratching from the Commercial Science team to solve!
Did you find the solution difficult or unusual?
This kind of result is quite normal for practical problem solvers who use maths to help businesses. They do not always have the problem statement clearly defined. To start to develop a solution to a real-world business problem they have to make certain assumptions. These assumptions are then updated as the results are analysed.
With thanks to the Tesco commercial science team.
