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Seventy tourists out of a group of 100 speak German 45 speak French and 23 speak both German and French.
How many tourists in the same group speak neither German or French. Use set notations
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Let G be the set of tourists speaking German, and n(G) is the number of people in this set ( n(G) = 70 ).
Let F be the set of tourists speaking French, and n(F) is the number of people in this set ( n(F) = 45 ).
Let FnG be the intersection of F and G. n(FnG) = 23.
Then the number of those who speal German OR French is the union of F and G and
n(F U G) = n(F) + n(G) - n(FnG) = 70 + 45 - 23 = 92.
Then the number of those who speaks neither German or French is 100 - 92 = 8.
Answer. 8.
See the lesson
- Counting elements in sub-sets of a given finite set
in this site.
Also, you have this free of charge online textbook in ALGEBRA-I in this site
- ALGEBRA-I - YOUR ONLINE TEXTBOOK.
The referred lesson is the part of this textbook under the topic "Miscellaneous word problems".