9
In a examination, 80% of the students passed in English, 85% in mathematics and 75% in both English and mathematics. If 40 students failed in both the subjects, the total number of students is?

• Total number of Students = 400
  
  Let the total number of students = x
  Let Students passed in English = A
  And Students passed in Maths = B
  Number of students passed in one or both the subjects = n(A?B)
  =n(A)+n(B)- n(A?B)
  =80% of x + 85% of x –75% of x
  =[(80/100)x+(85/100)x-(75/100)x]
  =(90/100)x
  =(9/10)x
  
  Students who failed in both the subjects = [x-(9x/10)]
  = x/10.
  
  Therefore, x/10= 40 of x =400
  Total number of students = 400.
  
• 12 years agoHelpfull: Yes(31) No(0)
• lets total number of student be x
  let A and B are passed in english and maths.. A=80% and B=85%..
  then the numeber of student passed in both the sub is 75%
  n(AUB)=n(A)+n(B)-n(AnB)=(80/100x + 85/100x - 75/100x)
  => 90/100x
  => 9/10x...
  student failed in both the sub=(x-9x/10)
  => x/10
  so,x/10=40
  x=400 student
  
• 12 years agoHelpfull: Yes(13) No(1)
• The total is 100%
  in English 80% and Maths 85% ,Both 75%
  we Need the percentage of students who Passed in the examination
  
  n(A)+n(B)-n(A intersection B)
  
  so (80% +85% )- 75% = 90%
  90 % of students passed in the examination
  
  the total is 100% where the passed students 90%
  so failed students 100%-90% =10%
  
  we know failed students=40
  
  A 10% of total students(X) =40 ,X we assume it as a total students
  
  X *10% =40
  so
  X*10/100=40 percentages method.
  
  X=40*100/10
  
  X=400
  
  so the total students is 400
• 12 years agoHelpfull: Yes(8) No(0)
• ans:130
  total no. of students who pased=80+85-75=90
  total no. of students who failed =40
  total no.of students=pass+fail=130
• 12 years agoHelpfull: Yes(4) No(15)
• Let the total number of students be x .
  Let A and B represent the sets of students who passed in English and Mathematics respectively .
  Then , number of students passed in one or both the subjects
  = n(AÈB)=n(A)+n(B)- n(AÇB)=80% of x + 85% of x –75% of x
  =[(80/100)x+(85/100)x-(75/100)x]=(90/100)x=(9/10)x
  Students who failed in both the subjects = [x-(9x/10)]=x/10.
  So, x/10=40 of x=400 .
  Hence ,total number of students = 400.
• 12 years agoHelpfull: Yes(2) No(0)
• 80%of x+85%of x -75%of x=9/10x
  students who fail in both the subjects=x-9/10x=x/10
  As, 40=x/10 since 40 students failed in both subjects
  
  total number of students=400
• 9 years agoHelpfull: Yes(0) No(0)