Q11 of 71 Page 30

In a group of 30 persons, 10 take tea but not coffee 18 take tea. Find how many take coffee but not tea, if each person takes atleast one of the drinks.

Given in a group of 30 persons, each one


takes at least one of the drinks.


So n(T∪C) = 30


n(T) = 18



Also given that number of persons drink only tea is 10.


There fore, number of persons drink both tea and coffee


n(T∩C) = n(T)–10 = 18–10 = 8


From the Venn diagram,


30 = 10 + 8 + x


x = 30 – 18


= 12


Number of persons drink only coffee not tea is 12.


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