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# Urgently need some probability (addition rule) help Watch

1. The addition rule is easy to do when its P(AUB) but Im having immense difficulty when its P(A'UB) or P(AUB'). I have the solution bank and have looked the Venn diagrams, I see which numbers they use but I cant seem to understand why.

2. Can you give an example of what you've been stuck on?
3. Goodness wasted so much time.

P(A'UB) would open up as

P(A') + P(B) - P(A'nB)

To get P(A'), simply '1 - P(A)' and P(A'nB) is easily read off from the Venn diagram.
4. (Original post by FirstDiscovery)
Goodness wasted so much time.

P(A'UB) would open up as

P(A') + P(B) - P(A'nB)

To get P(A'), simply '1 - P(A)' and P(A'nB) is easily read off from the Venn diagram.
Yes, ok. But what about it don't you understand?

Do you understand why

Or why ?
5. (Original post by ekudamram)
Yes, ok. But what about it don't you understand?

Do you understand why

Or why ?
Thanks for bringing those up as I ran into them earlier. The book doesnt show everything.

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