You have been randomly and anonymously paired with another participant. One of you will be selected at random to be participant A; the other will be participant B. You will learn whether you are participant A or B prior to making any decision.

To start, participant A receives 100 points; participant B receives nothing. Participant A can send some or all of his 100 points to participant B. Before B receives this amount, it will be multiplied by 3. Once B receives the tripled amount he can decide to send some or all of it to A.