Question

in a group of 25 persons 8 drink only tea 7drink only coffee and 4 persons drink tea and coffee how many of them neither drink tea norcoffee

Answer 1

let us consider there are 2 sets
1)a=who drinks tea
2)b=who drinks coffee and s=no.of persons
by given information,
n(anb)=4,n(a)=8,n(b)=7,n(s)=25
~n(aub)=n(a)+n(b)-n(anb)
~n(aub)=8+7-4=11
then no.of persons who neither drinks tea nor coffee=s complement=n(s)-n(aub)
=25-11=14

Answer 2

10 people did't drink coffee neither tea