Question

✰ QUESTION :

➽ In a class of 120 students numbered 1 to 120, all even numbered students opt for Physics, those whose numbers are divisible by 5 opt for Chemistry and those whose numbers are divisible by 7 opt for Math. How many opt for none of the three subjects?

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Answer 1

Let n(A)= number of students opted Mathematics =70,

n(B)= number of students opted Physics =46,

n(C)= number of students opted Chemistry =28,

n(A∩B)=23,

n(B∩C)=9,

n(A∩C)=14,

n(A∩B∩C)=4,

Now n(A∪B∪C)

=n(A)+n(B)+n(C)−n(A∩B)−n(B∩C)−n(A∩C)+n(A∩B∩C)

=70+46+28−23−9−14+4=102

Si number of students not opted for any course = Total −n(A∩B∩C)

=140−102=38.

Answer 2

Answer:

The answer for he question is 38