In the pill riddle the situation is this: every morning you have to take two pills, one red and one bluewhich you keep in two separate boxes. So one morning, like every morning, you get ready to take your two medicines, but the light goes out and the room remains completely dark (there is also a version of the riddle in which there is no the light goes outbut whoever has to take the pills is blind, but the question remains the same).
However, something unexpected happens: the two pills fall to the floor. For this reason, you decide to take two more, one from each box, so as to make sure you have a red pill and a blue pill in your hand. But unfortunately… they fall again! But not only that, the pills inside the boxes are finished. So you end up with four pills on the floor, two red and two blue, that you can’t distinguish from each otherof which you must be able to get exactly one red and one blue. How to do it?
The solution to the red and blue pill riddle
The first thought that comes to mind is to think in a probabilistic sense, thinking about what the probability of drawing exactly one blue and one red pill from a group of four pills, two of which are red and two blue. Leaving aside the probabilistic calculations, there is no case in which one can be certain of having drawn a red and a blue pill!
So, how to do it? The answer lies in… dividing them! If we collect all four pills, put them in a row and cut them all in half, choosing all the upper halves – or all the lower halves – we will be sure to have exactly two blue halves and two red halves, and therefore exactly one blue pill and one red pill, and without needing the help of light (or sight)!
