SAT Math: Determine if events are independent
19+ practice questions in Praczo
The concept, explained
- 1
Two events A and B are independent if the occurrence of one does not change the probability of the other: P(A | B) = P(A).
- 2
Equivalently, for independent events, P(A and B) = P(A) · P(B). If this equation fails, the events are dependent.
- 3
In a two-way table, check independence by comparing P(A | B) with P(A). If they match, the events are independent.
- 4
Real-world hint: drawing cards WITH replacement keeps draws independent; WITHOUT replacement makes them dependent.
- ✗ Assuming events are independent because they seem unrelated. You must verify with probabilities.
- ✗ Adding probabilities instead of multiplying when computing P(A and B) for independent events.
SAT-style practice
A fair coin is flipped twice. What is the probability of getting heads on both flips?
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