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Given that events A and B are independent with P(A n B)=0.3 and P(A u B')=0.3, find P(A u B).
It's supposed be quite basic as its only 3 marks, but I think I'm missing something as I can't figure it out...anyone know?
Thank you for your help
Last edited by Carisma (2010-01-08 01:19:29)
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I think there may be a mistake with the question, because I didn't use their independence and it just doesn't seem right.
Taking P(A u B') = 0.3 and negating it, we get P(A' n B) = 0.7.
Since we also have that P(A n B) = 0.3, we now know that P(B) = 1.
Hence, P(A u B) = 1 also.
Why did the vector cross the road?
It wanted to be normal.
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Hi Carisma;
A and B are independent with P(A n B)=0.3
I agree if they were independent how could the intersection of A , B be anything but 0?
Welcome to the forum!
In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.
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You're thinking of mutually exclusive. If events A and B are independent it means that P(B) = P(B|A) = P(B|A'), and vice versa.
Why did the vector cross the road?
It wanted to be normal.
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Hi,
Yep, definitions, I can never remember them.
In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.
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