in an examination 70% of the candidates passed in history and 50% in geography and 20% failed in both the subjects.if 500 students passed in both the subjects,then how many candidates appeared for the exam?

• no. of students passed in geography and history=(100-20)=80%
  so,{(hist) U (geo)}=(hist)+(geo)-(hist&geo)
  =70+50-80
  =40
  a/c,40%=500
  therefore 100%=(500*100)/40
  =1250
  so,ans is 1250
• 11 years agoHelpfull: Yes(51) No(3)
• ans=1250
  let total student=x,then
  x-0.2x=0.7x+0.5x-500,
  x=1250
• 11 years agoHelpfull: Yes(39) No(3)
• x=70x/100 +50x/100-500
  x=140x-50000/100
  x=1250
  
  
• 11 years agoHelpfull: Yes(7) No(9)
• 1250
  using formula,
  P(AorB)= P(A)+ P(B)- P(A&B)
• 11 years agoHelpfull: Yes(4) No(1)
• it is given that 20% student failed in both the subject it means that 80% student passed in both subjects and 500 student passed in both subjects.
  80% of total no of students=500
  hence total no of student is 625.
  Ans is 625
• 11 years agoHelpfull: Yes(4) No(19)
• because P(A)=7/10 P(B)=5/10 P(AuB)=1-(2/10)=8/10
  THEREFORE P(A&B)=P(A)+P(B)-P(AUB)=4/10
  Because 40% of x=500(given)
  so x=1250 which is the total no of candidates appeared.
• 11 years agoHelpfull: Yes(3) No(2)
• A=History,B=Geography
  no of students passed in A and B =(100%-20%)=80%
  N(A)=70,N(B)=50,N(AuB)=80%
  so,
  N(AUB)=N(A)+N(B)-N(AUB)
  =70%+50%-80%
  =120%-80%
  =40%(500),20%(250)
  THEREFORE 100%=(40%*2=80%(1000)+20%(250))
  SO,ANS IS =100%(1250)
• 11 years agoHelpfull: Yes(2) No(1)