Coin Flip Probability

Solution

At 99 flips, you either have an odd or even number of heads. So the probability entirely depends on the last flip, making the answer 1/2.

Apparently this was a QFS interview question. We were talking about this after an 8am discrete math lecture. QFS and BAC Quant ran their interviews around the same time, I guess. I heard quant conversations in the library for like a week, lol.