In an examination ,80% student passed in physics ,70% in chemistry while 15% failed in both the subject.if 325 students passed in both the subjects.Find the total no. of student who appeared in the examination.

1) 500
2) 400
3) 300
4) 600

• answer 500
• 11 years agoHelpfull: Yes(3) No(4)
• Answer. 1) 500
  Explanation.
  T - total number of students.
  80% student passed in physics ,70% in chemistry
  20% failed in physics , 30% failed chemistry and 15% failed both
  No. of student who failed at least in one subject = 0.20T + 0.30T - 0.15T = 0.35T
  That is 0.35T or 35% of students failed at least on subject or we can say 65%(T-0.35) of students passed in both the subjects(Since T = failed in both + atleast one + failed in none(Passed both)).
  
  So 0.65T = 325
  T = 500
• 6 years agoHelpfull: Yes(1) No(2)
• 1) 80% students passed in physics. 20% students failed in physics
  2) 70% students passed in chemistry. 30% students failed in chemistry.
  3) 15% students failed in both exams
  
  20 + 30 - 15 = 35% students failed in both exams.
  Hence , 65% students passed in both exams
  
  65% of x = 325
  X = 500
• 6 years agoHelpfull: Yes(1) No(1)
• 80% of students passed in physics+70% of students passed in chemistry +325 students who passed in both+15% who failed in both= total no of students
  
  Let x be total no of students then solution is,
  
  0.8x+0.7x+325+0.15x=x
  
  Solving the above equation gives 500.
• 8 years agoHelpfull: Yes(0) No(7)