Sets Relations And Functions Question 28
Question: In a town of 10000 families, it was found that 40% families buy newspaper A, 20% families buy newspaper B and 10% families buy newspaper C, 5% buy A and B, 3% buy B and C and 4% buy A and C. if 2% families buy all of three newspapers, then the number of families which buy A only, is
Options:
A) 4400
B) 3300
C) 2000
D) 500
Show Answer
Answer:
Correct Answer: B
Solution:
- [b] $ n(A)=40 $ % of $ 10000=4000,n( B )=2000, $ $ n(C)=1000,m(A\cap B)=500,n(B\cap C)=300, $ $ n(C\cap A)=400,n(A\cap B\cap C)=200 $
$ \therefore n(A\cap \overline{B}\cap \overline{C})=n{ A\cap (B\cup C)’ } $ $ =n(A)-n{A\cap (B\cup C)} $ $ =n(A)-n(A\cap B)-n(A\cap C)+n(A\cap B\cap C) $ $ =4000-500-400+200=3300. $
BETA
