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    Hello, I need help with this probability problem and would appreciate any help.

    A and B are equally likely.
    The chance of A or B happening is .70
    The chance of both A and B happening is .40
    What is the chance of event A happening?

    Thank you!

    5.5 (I think)

    Just sketched the Venn diagram and thats the only answer I could come up with.

    No guarantees it right though

    Just event A is .15 if A or B means at least one of A or B. If it means only one of A or B, the Q is wrong because that would put the total prob at 1.1, which i doubt, so it is most likely .15

    this is how u do it folks:

    p(a) = p(b)
    P(a or b) = 0.7
    P(a and b) = 0.4

    using the addition rule which is " p (A or B) = p(a) + p(b) - p(a and b)"

    let p(a) = x (so P(b) will also = x)

    0.7 = x + x - 0.4
    1.1 = 2x
    x = 0.55

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