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VICMath MethodsQuick questions
Unit 3
Quick questions on Probability, conditional probability and independence: VCE Math Methods Unit 3
6short Q&A pairs drawn directly from our worked dot-point answer. For full context and worked exam questions, read the parent dot-point page.
What is worked example?Show answer
In a class of 30 students, 18 study Methods, 12 study Specialist, and 8 study both. A student is chosen at random.
What is forgetting to subtract the overlap in the addition rule?Show answer
$P(A \cup B) = P(A) + P(B) - P(A \cap B)$. Skipping the subtraction overcounts.
What is confusing $P $ with $P $?Show answer
The conditional probability divides by $P(B)$; the intersection probability does not.
What is confusing independence with mutual exclusivity?Show answer
These are different concepts and usually contradict each other (for events with positive probabilities).
What is assuming independence without justification?Show answer
Two events are not independent just because they "feel unrelated". Always test using $P(A \cap B) = P(A) P(B)$.
What is treating "without replacement" as independent?Show answer
Drawing without replacement creates dependence: the second probability is conditional on the first.
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