Probability basics: Outcome = single result; Sample space = all possible outcomes; Event = subset of sample space. P(E) = favorable outcomes / total outcomes (classical). For equally likely outcomes: P(E) = |E|/|S|. Properties: 0 ≤ P(E) ≤ 1; P(S) = 1; P(∅) = 0. Example: Die roll. S = {1,2,3,4,5,6}. Event 'even' = {2,4,6}. P(even) = 3/6 = 0.5. Complement: P(E') = 1 - P(E). P(not even) = 1 - 0.5 = 0.5. Solving: Identify sample space; count favorable; calculate ratio. Exam tip: Understand classical probability. Recognize equally likely assumption. Practice: Various probability scenarios.