Description:
প্রশ্ন: 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 subject ?
ব্যাখ্যা:
Physics takes =120/2=60
Chemistry takes =120/5=24
Mathematics takes =120/7=17
Physics and chemistry =120/10=12
Physics andmathematics =120/14=8
Chemistry and mathematics = 120/35=3
Physics, Chemistry and mathematics =120/70=1
So, Only physics and chemistry =12-1=11
Only physics and mathematics =8-1=7
Only Chemistry and mathematics =3-1=2
Now, Only physics =60-11-7=41
Only Chemistry =24-11-2-1=10
Only mathematics =17-7-2-1=7
Shortcut not taken none ofthe three =120-(41+10+7+11+7+2+1)=12-79=41