- #1
TheMathNoob
- 189
- 4
Homework Statement
In a certain city, three newspapers A, B, and C are published. Suppose that 60 percent of the families in the city subscribe to newspaper A, 40 percent of the families subscribe to newspaper B, and 30 percent subscribe to newspaper C.Suppose also that 20 percent of the families subscribe to both A and B, 10 percent subscribe to both A and C, 20 percent subscribe to both B and C, and 5 percent subscribe to all three newspapers A, B, and C. what percentage of the families subscribe to exactly one of the newspapers.
Homework Equations
P(AUB)=P(A)+P(B)-P(BnC)
3. The Attempt at a Solution [/B]
I already find the percentage of the families that subscribe to at least 1 newspaper which resulted to be 85%. Doing the set thing, I realized that I have to find A B and C without the intersections like shading the whole area except for the complement and the intersections. I tried to subtract the 85% previously found from the the total sum of the intersections. Like this
A U B U C - A n C-A n B-B n C-A n B n C
But this is wrong because 1 person can be in one or more intersections.
There is solution in this website which I think that is wrong because they just add the intersections without realizing that one person can be in more than one intersections.
https://cseweb.ucsd.edu/classes/sp97/cse21/quizzes/q3solsph/q3solsph.html
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