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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❒ Explanation needed !!
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Answer 1

Answer:

the answer is 41.  

Explanation:

A is the set of those who opted for Physics = 1202 = 60 students

B is the set of those who opted for Chemistry = 1205 = 24

C is the set of those who opted for Math = 1207 = 17.

Number of students who opted for Physics and Math

Number of students who opted for Chemistry and Math

60 + 24 + 17 - (12 + 8 + 3) + 1 = 79.

Number of students who opted for none of the three subjects = 120 - 79 = 41.