This is very hard brain teaser.
A man has a medical condition that requires him to take two kinds of pills, call them P1 and P2. The man must take one P1 pill and one P2 pill each day, or he will die. If he takes more than 1 pill of the same kind per day, he will die. Both pills look exactly the same (same weight, color, shape, size, etc…;).
The pills are taken by first dissolving them in water.
One day, as he is about to take his pills, he takes out one P1 pill from the P1 jar and puts it in a glass of water. Then he accidentally takes out two P2 pills from the P2 jar and puts them in the water. Now, he is in the situation of having a glass of water with three dissolved pills, one P1 pill and two P2 pills. Unfortunately, the pills are very expensive, so the thought of throwing out the water with the 3 pills and starting over is out of the question.
How should the man proceed in order to get the right quantity of P1 and P2 while not wasting any pills?
Add one more P1 pill to the glass and let it dissolve.
Take half of the water today and half tomorrow.
So, Percentage of Pill P1 and Pill P2 on both the day in overall be managed equal.
It works under following assumptions:
The dissolved Pills can be used next day.