Question 86682
Draw a vendiagram and use the given information to fill in the number of elements for each region. 
n (A ' ) = 28 , n(B) = 25, n (A' U B ' ) = 45, n(A (upside down U ) B )=12 
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Draw two intersecting circles inside a rectangle.
Label them A and B.
Put a 12 in the intersection of A and B.
Since B has 25 put 25-12 = 13 in the remaining section of B.
Since A' is 28 put a 28-13 = 15 in the rectangle but in neither circle.
Since (A' OR B') = (A and B)' put 45-(13+15)=17 in the unnumbered region
of A.
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Problem #2 

Let A and B independent events with P (A) = (1)/(4) and P(B) = (1)/(5).
Find P(A (Upside down U) B)
since A and B are independent the answer is (1/4)(1/5) = 1/20
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P(A U B) = P(A)+P(B)-P(A intersect B) = 1/4 + 1/5 - 1/20 = 8/20 = 2/5
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Problem #3
In the previous section, we described an experiment in which the numbers 1, 2, 3, 4, and 5 are written on slips of paper, and 2 slips are drawn at random one at a time without replacement. Find each probability 
The probability that the first number is 3, given the following.
a. The sum is 7.
b. The sum is 8. 
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Answered Previously.
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Cheers,
Stan H.