Probability is one of the most read-carefully sections on the paper. The math is not hard. Deciding which formula applies is the hard part, and it is almost always a reading problem.
Two questions to ask first: is this with or without replacement, and is order relevant? These two answers determine whether you are counting combinations, permutations, or something else entirely.
For conditional probability, write out P(A|B) = P(A∩B) / P(B) explicitly before plugging numbers. Half the mistakes on this topic come from computing P(A∩B) and calling it P(A|B).
Expected value questions on the gaokao almost always reduce to E(X) = Σ xᵢ · pᵢ. Build the distribution table before writing the formula.
For the normal-distribution question at the end of the section, memorize the three intervals (μ±σ ≈ 68.3%, μ±2σ ≈ 95.4%, μ±3σ ≈ 99.7%). The question tests whether you can read a table, not integrate.