Question 472828
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Hi,
event A contains 10 observations and event B contains 15 observations.
intersection of events A and B contains exactly 3 
how many observations are in the union of these two events:
 P(A &#8746; B) = P(A) + P(B) - P(A &#8745; B)  = 10 + 15 - 3 = 22