An investigator interviewed 100 students to determine the performance of three drinks : milk, coffee and tea. The investigator reported that 10 students take all three drink milk, coffee and tea ; 20 students take milk and coffee; 25 students take milk and tea ; 20 students take coffee and tea; 12 students take milk only; 5 students take coffee only and 8 students take tea only. Then the number of students who did not take any of three drinks is
Correct option is D. 30
Let,
n(M) be the number of students who drink milk only
n(T) be the number of students who drink tea only
n(C) be the number of students who drink coffee only
Given:
n(M)=12,n(C)=5 and n(T)=8, n(M∩C∩T)=10
⇒n(M∩C)=20−n(M∩C∩T)=20−10=10
Also n(M∩T)=25−n(M∩C∩T)=25−15
Also n(T∩C)=20−n(M∩C∩T)=20−10=10
∴ Number of students who take all the drinks
=n(M)+n(C)+n(T)+n(M∩C)+n(M∩T)+n(T∩C)+n(M∩C∩T)
=12+5+8+10+15+10+10=70
∴ Number of students who did not take any of the drink =100−80=30 students.