Question

in an examination of a certain class, at least 70% of the students failed in physics , at least 72% failed in chemistry , at least 80% failed in mathametics and at least 85% failed in english. how many at least must have failed in all the four subjects

Answer 1

Number of students failed in Physics = atleast 70%
Number of students failed in Chemistry = atleast 72%
Number of students failed in Maths = atleast 80%
Number of students failed in English = atleast 85%

That  means,
Number of students passed in Physics = atmost 30%
Number of students passed in Chemistry = atmost 28%
Number of students passed in Maths = atmost 20%
Number of students passed in English = atmost 15%

∴ Total number of students passed in all subjects = atmost ( 30+28+20+15) % = 93%
   Total number of students failed in all the subjects = atleast (100 - 93)% =         7%




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