I would tell her that her prediction is inaccurate because it isn’t guaranteed that the coin will land on both sides an equal amount of times. It’s possible that the coin could land heads up more often than it could land tails up or the other way around.
What I would tell Charli is that his prediction is somewhat right because there is a 50/50 chance of landing the coin on each side because 325 is half of 650.
