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# Probability Problem watch

1. 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!
2. 5.5 (I think)

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

No guarantees it right though
3. 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
4. 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
5. p

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