SOLUTION: A survey of a group's web habits for the past month obtained the following information. 30% visited Facebook. 38% visited LinkedIn. 36% visited Google. 16% visited Facebook a

Question 1205866: A survey of a group's web habits for the past month obtained the following information.
30% visited Facebook.
38% visited LinkedIn.
36% visited Google.
16% visited Facebook and LinkedIn.
16% visited Facebook and Google.
18% visited LinkedIn and Google.
9% visited all three sites.
Find the percentage that visited none of these three sites last month.
Hint: Draw a Venn diagram for three sets. Then label appropriate parts from the given information.
Answer by ikleyn(52776) (Show Source): You can put this solution on YOUR website!
.


Find the percentage of those who visited at least on of the three sites.

Use the Inclusion-Exclusion principle/formula

    
    30% + 38% + 36% - 15% - 16% - 18% + 9% = 64%.


The percentage of those who visited none of these three sites last month 
is the complement of 64% to 100%, i.e.  100% - 64% = 36%.


ANSWER.  36%.

Solved.

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On inclusion-exclusion principle, see this Wikipedia article

https://en.wikipedia.org/wiki/Inclusion%E2%80%93exclusion_principle

To see many other similar (and different) solved problems, see the lessons

    - Counting elements in sub-sets of a given finite set
    - Advanced problems on counting elements in sub-sets of a given finite set
    - Challenging problems on counting elements in subsets of a given finite set
    - Selected problems on counting elements in subsets of a given finite set
    - Inclusion-Exclusion principle problems

in this site.

Happy learning (!)

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