Question

In a class of 50 students, each one cone to school by bus or by bicycle or on foot. 25 bus, 20 by bicycle, 30 on foot and 10 students by all the three. now how many students come to school exactly by two modes of transport lesson is set language

Answer 1

50 is the number of total students

So the students who come on bus = - n(A)= 25

And the students who use bicycle = - n(B) = 20

And the ones who come by foot = - n(C) = 30

Total number of students are:  - n(A∪B∪C) = 50

Total number of students who come to school using different modes of transport: - n(A∩B∩C) = 10

n(A∪B∪C) = n(A)+n(B)+n(C)-n(A∩B)-n(B∩C)-n(C∩A)+n(A∩B∩C)

50 = 25 + 20 +30 - n(A∩B) - n(B∩C) - n(C∩A) + 10

50 = 85 - n(A∩B) - n(B∩C) - n(C∩A)

n(A∩B) - n(B∩C) - n(C∩A) = 85 - 50

n(A∩B) - n(B∩C) - n(C∩A) = 35

35 is the final answer for this question.

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