Probability: combined events — KCSE Mathematics
KCSE Mathematics · 104 practice questions · 4 syllabus objectives
What You'll Learn
Key learning outcomes for this topic, aligned to the KNEC KCSE syllabus.
Apply the addition rule P(A ∪ B) = P(A) + P(B) – P(A ∩ B) for any two events; simplify for mutually exclusive events
Apply the multiplication rule P(A ∩ B) = P(A) × P(B|A) for dependent events and P(A) × P(B) for independent events
Use tree diagrams and two-way tables to represent and calculate probabilities for two-stage and three-stage experiments
Probability: combined events
Sample Questions
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A bag contains 3 red balls and 2 blue balls. If one ball is drawn at random and not replaced, calculate the probability of drawing a red ball first and then a blue ball. (3 marks)
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In a class, the probability that a student studies Mathematics is 0.6. If a student studies Mathematics, the probability that they also study Physics is 0.8. Calculate the probability that a randomly selected student studies both Mathematics and Physics. (4 marks)
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A box contains 5 red balls and 3 blue balls. If a red ball is drawn first and not replaced, find the probability of drawing a blue ball second. (3 marks)
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In a class, the probability that a student studies mathematics is 0.6 and the probability that the same student studies physics is 0.4. If the probability that a student studies both subjects is 0.2, calculate the probability that a randomly selected student studies either mathematics or physics. (4 marks)
Why Practise Probability: combined events?
KNEC Aligned
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