Solve the following problems and verify the data in each case by drawing Venn diagrams. In a class, 50 students offered Mathematics, 42 offered Biology and 24 offered both the subjects. Find the total number of students in the class.
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Solution
Let the total number of students who offered mathematics be n(M) and number of students who offered biology be n(B).
Then, the number of students who offered both mathematics and biology is n(M∩B).
We know that n(A∪B)=n(A)+n(B)−n(A∩B) where A and B are the respective sets.
Here, it is given that in a class, 50students offered mathematics, 42offered biology and 24 offered both the subjects, that is n(M)=50,n(B)=42 and n(M∩B)=24 and therefore,
n(M∪B)=n(M)+n(B)−n(M∩B)=50+42−24=92−24=68
Hence, the total number of students in the class is 68.