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Venn diagrams with LOTS of circles

  • 22-02-2006 4:12pm
    #1
    Pigman II
    Closed Accounts Posts: 10,921 ✭✭✭✭


    If you have two intersecting cirles P(A) and P(B)

    (iirc?) then P(A U B) = P(A) + P(B) - P(A n B)

    Anyway, I was just wondering is there a general formula for this if you have 3 circles (ie P(A U B U C) ) or 10 circles or 1000 circles that all intersect each other?

    Thanks!


Comments

  • #2
    Chucky
    Closed Accounts Posts: 528 ✭✭✭Chucky


    From looking at a Venn Diagram of three intersecting circles I have figured out that P(AuBuC) equals:

    P(A) + P(B) + P(C) – P(AnB) – P(AnC) – P(BnC) + P(AnBnC)

    Just look at a Venn Diagram yourself and you'll see that it makes sense. For any more than three circles it gets a bit messy!


  • #3
    Pigman II
    Closed Accounts Posts: 10,921 ✭✭✭✭Pigman II


    Yep, that's the idea alright. Just wondering if there's a general formula for as many circles as you one would wish.


  • #4
    Chucky
    Closed Accounts Posts: 528 ✭✭✭Chucky


    Arrrgh! I have looked on the world-wide-web but cannot find any general formula. There is probably something somewhere but it's remoteness would be admirable! Perhaps you should get in contact with your maths lecturer again and/or e-mail a Mathematician in another university.


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