IB Maths AA SL 4.5 - Intro to Probability

This IB Maths AA SL Topic 4.5 – Introduction to Probability resource introduces students to the fundamental language and principles of probability. It begins by defining key terms including experiment, trial, outcome, event, equally likely outcomes, and sample space. Students learn how to represent the sample space using U and calculate the probability of an event using P(A) = n(A)/n(U).

The lesson also develops students’ understanding of experimental probability, or relative frequency, and how repeated trials tend to produce results that approach theoretical probability. Students explore complementary events and use the relationship P(A’) = 1 - P(A) to calculate the probability that an event does not occur. The resource also introduces the expected number of occurrences using expected frequency = number of trials × probability. With clear definitions, visual examples, coin and dice contexts, worked problems, complement strategies, and fully worked solutions, this resource helps SL students build a strong foundation in probability in line with IB Mathematics AA expectations.