1. Prove A intersection (A U B)' = phi

 

2. Prove that if A U B = C and A intersection B = phi, then C - B = A.

 

3. In ao town of 10,000 families it was found that 40% families buy  newspaper A, 20% families buy newspaper, 10% families buy newspaper C, 5% buy A and B, 3% buy B and C, 4% buy A and C, If 2% buy all three papers, then find the number of families which buy newspaper A only.

Hi!
Here is the answer to your question.
For 1st question

So, the relation is proved.

For 3rd question
Let A denote the set of families buying the newspaper A.
Let B denote the set of families buying the newspaper B.
Let C denote the set of families buying the newspaper C.
Then, by the given information,
n (A) = 40% of 10,000 = 4000, n (B) = 20% of 10,000 = 2000, n (C) = 10% of 10,000 = 4000

Now, the given information can be represented using Venn diagram as,

From the diagram, it is clear that:
Number of families which buy newspaper A only
= n (A) – (300 + 200 + 200)
= 4000 – 700 = 3300
 
Cheers!

  • 11

why do  u rply so lte....?.......it's been 2 weeks since i akked u 3 questions n no rply hve cmne so fr...if dis iz the way 2 treat 2 ur paid members i wnt u 2 gve my money bck

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