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Sorry to be a burden but my maths exam is tomorrow and I have no idea how to do this at all. Here is the exact question :

The two independent events $A$ and $B$ are such that $P(A) = 0.2$, $P(A\cup B) = 0.4 $.

  • a. Evaluate $P(B)$.
  • b. Find the probability that at least one of the two events occurs.
  • c. Given that exactly one of the events occurs, find the probability that $A$ occurs.

I need help with the entire question really, but at least part a.

Thanks in advance!

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    What is the _definition_ of independent events? What is $P(A \cup B)$ in terms of $P(A)$, $P(B)$, etc? Is it true that $x - xy = x(1-y)$ where $x$ and $y$ are real numbers?2011-12-12
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    (b) is $P(A \cup B)$. (c) is $\dfrac{P(A)-P(A \cap B)}{P(A \cup B) -P(A \cap B)}$2011-12-12
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    @Dilip. I think not. It could be $P(A) + P(B) - 2P(A\cap B)$.2011-12-12

2 Answers 2