Question 1052806
 in a survey of 100 families,the numbers that read the most recent issues of various magazines were found to be as follows:
reader digest=28, science today = 30 ; caravan = 42
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reader digests and science today =8
reader digest and caravan=10,
science today and caravan=5
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all the three magazines=3. 
how many read none of the three magazines?
how many read caravan as their only magazines? 
how many read science today if and only if,they read caravan? 
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Sketch a Venn Diagram: a rectangle containing 3 intersecting circles.
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Work from inside to the outside::
Put 3 in the intersection of all three circles
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Put 5 -3 = 2 in the intersection of sci and caravan
Put 8-3 = 5 in the intersection of digests and science
Put 10-3 = 7 in the intersection of digest and caravan
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The remainder of readers digest has 28-5-7-3 = 13
The remainder of science = 30-2-5-3 = 20
The remainder of caravan = 40 -7-2-3 = 28
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Total number in the circles is 80
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Number of families in the rectangle but not in the circles = 20 
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how many read none of the three magazines?:: 20 
how many read caravan as their only magazines?:: 27 
how many read science today if and only if,they read caravan?:: 10
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Cheers,
Stan H.
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