Solution to the Pearls Problem
The solution is shown in three figures. Start with figure 1.
The key is to track the change in the heavy (or lighter) side of the scale as pearls are moved from one side to the other. This allows us to not only detect the defective pearl, but also to known if it is lighter or heavier.
Figure 1.
Figure 2.
Figure 3.
Another solution, from my dad, uses the same process for the case depicted in figure 3, but uses a different approach to the cases depicted in figures 1 and 2. This solution relies on the ability(shown in figure 3) to identify in just one weighting the defective pearl from a group of 3 pearls, when we know if the defective pearl is lighter or heavier (determined by the logic of the previous moves)
