✰ 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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➽ 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?
❒ Try not to spam !!
❒ Explanation needed !!
❒ I'ill appretiate good responders!!
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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:
The answer for he question is 38