Exercise · ZW-INDEPENDENCE-OF-EVENTS-004 · ★☆☆ Basic
If \(P(A)=0.5\), \(P(B)=0.4\) and \(P(A\cap B)=0.3\), which statement is correct?
Choose one option.
Show answer
- B. They are not independent: \(0.3\ne0.5\cdot0.4=0.2\)
Explanation
The product is \(0.2\) and the intersection is \(0.3\); they differ, so there is dependence (indeed \(P(A\mid B)=0.75\ne0.5\)).
Review the concept: Independence of events
Two events \(A\) and \(B\) are independent when knowing that one occurred does not change the probability \(P\) of the other.
\[P(A\cap B)=P(A)\,P(B)\]
More practice problems: independence of events
- ZW-INDEPENDENCE-OF-EVENTS-001 If A and B are independent with P(A)=0.3 and P(B)=0.5, what is P(A∩ B)?
- ZW-INDEPENDENCE-OF-EVENTS-002 Two fair coins are tossed. What is the probability of getting two heads?
- ZW-INDEPENDENCE-OF-EVENTS-003 If P(A)=0.4, P(B)=0.5 and P(A∩ B)=0.2, are they independent?
- ZW-INDEPENDENCE-OF-EVENTS-005 If A and B are independent with P(A)=0.6 and P(B)=0.5, what is P(A| B)?
- ZW-INDEPENDENCE-OF-EVENTS-006 If A and B are independent with P(A)=0.3 and P(B)=0.2, what is P(A∪ B)?
- ZW-INDEPENDENCE-OF-EVENTS-007 A fair coin is tossed three times. What is the probability of at least one head?
- ZW-INDEPENDENCE-OF-EVENTS-008 A fair die is rolled. Let A: «even» and B: «1 or 2». Are they independent?
- ZW-INDEPENDENCE-OF-EVENTS-009 Let A and B be independent events with positive probabilities. Can they be mutually exclusive?
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