Basic mathematics skills (manipulating real numbers, integrating functions over a real interval, concept of derivative and antiderivative functions).
Basic probability theory: uniform distribution, probability of an event, toss of a coin, etc. You may have a look to the pdf file given below. This is a rather mathematical presentation, please don’t be afraid of it and take your time to read the beginning of the file. You may skip parts thereof. We will cover together part of this.