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VICMath MethodsQuick questions
Unit 1: Functions, relations and graphs
Quick questions on Probability rules and combinations (VCE Maths Methods Unit 1)
11short 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 complement?Show answer
$P(A^c) = 1 - P(A)$.
What is addition rule?Show answer
$P(A \cup B) = P(A) + P(B) - P(A \cap B)$. For mutually exclusive events, $P(A \cap B) = 0$.
What is multiplication rule?Show answer
$P(A \cap B) = P(A) \cdot P(B|A)$. For independent events, $P(B|A) = P(B)$, so $P(A \cap B) = P(A) P(B)$.
What is conditional probability?Show answer
$P(B|A) = P(A \cap B)/P(A)$, the probability of $B$ given $A$ has occurred.
What is multiplication principle?Show answer
If task $1$ has $n_1$ ways and task $2$ has $n_2$ ways, then the combined task has $n_1 \cdot n_2$ ways.
What is permutations?Show answer
Arrangements of $r$ items from $n$:
What is combinations?Show answer
Selections of $r$ from $n$:
What is using $^nP_r$ instead of $^nC_r$?Show answer
For unordered selections, use combinations.
What is forgetting "without replacement" reduces the population?Show answer
After one draw, the second draw is from $9$, not $10$.
What is treating dependent events as independent?Show answer
Conditional probability is needed when events influence one another.
What is forgetting the intersection in the addition rule?Show answer
$P(A) + P(B)$ counts $P(A \cap B)$ twice.