I just had a research analyst interview where I was asked a tough question. Suppose you have a coin that's not fair - 70% will be heads and 30% tails. How could you change these probabilities to 50% heads and 50% tails. I think interviewer wanted to know how to build a system and how to adjust for this bias. I suggested making 2 of the heads tails but was told 'how would you know which to change'. Any ideas?
