Math 340                                                        
	   Remarks and Hints Related to Homework Problems
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Below for the complement of an event A I will use A^c, and for the intersection
of two events A and B I will either use AB or (A int B).
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(p.45, #3)
   
   Apply the def of conditional prob,  namely, 

   P(A|B) = P(AB) / P(B)
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(p.45,  #5)

    Note here that there are two ways that a black ball can be drawn:
    Either urn 1 is selected and a black ball is drawn from it,  or
    urn 2 is selected and a black ball is drawn from it.  

    Now apply the Law of Total Probability.
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(p.45,  #7)
    
    a.  Recall the formula that we derived in class for P(A U B).
    b.  Recall the def of independence for two events.
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(p.45,  #9)
    
    Here first using words describe for yourself why A and B are not
    equivalent.  You may want to think along the lines:

    What is the probability that a student selected belongs to 
    high school (i) under scheme A;  as opposed to the selection 
    procedure of scheme B.
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