Most tested topics (2020-2024):

1. Bayes' theorem (bags, machines, defective items)
2. Binomial distribution (finding probabilities, mean/variance)
3. Complement method (at least one success)
4. Conditional probability (given information, restricted sample space)
5. Classical counting (balls, cards, dice)

Difficulty distribution:

• 30% easy (direct formula, complement)
• 50% medium (Bayes', binomial computation)
• 20% hard (multi-step conditional, parameter finding)

Time targets:

• Basic probability (complement, addition rule): 1-2 minutes
• Conditional/Bayes': 2-3 minutes
• Binomial computation: 2-3 minutes
• Complex multi-step: 3-4 minutes

Recurring patterns:

• "A ball drawn from one of several bags" → Bayes'
• "n independent trials, P(at least k)" → Binomial + complement
• "Given that event A occurred, find P(B)" → Conditional
• Truth-teller/liar + dice → Bayes' classic