I mentioned this before -I think I mentioned it before -if you say, I'm going to ask you to bet on a coin toss.

我之前提到过...,应该提到过...,我邀请你与我赌硬币正反面

耶鲁公开课 - 金融市场课程节选

You might say the probability that you toss a coin and it comes up heads is a half, because it's equally likely to be heads and tails.

如果你抛一枚硬币,正面向上的概率一定是50%,因为正反哪一面向上的可能性是相同的

耶鲁公开课 - 金融市场课程节选