There are 100 in a class and they attend a test. 20 students are failed in both the subjects. 50 students pass in subject A. 60 students passed in subject B. How many students passed in subject A only.

• n(A)=50
  n(B)=60
  Total number of students attended test=100
  number of students fail in both subject=20
  So, number of students who pass in both subject n(AUB)=100-20=80
  n(AUB)=n(A)+n(B)-n(A∩B)
  80=50+60-n(A∩B)
  n(A∩B)=30
  so, number of students pass for subject A only=50-30=20
  Ans : 20
• 9 years agoHelpfull: Yes(22) No(0)
• ANS: 20
  
  LET x be the total no. of students who passed in both test.
  Then, no. of students who passed in A only= total no. of students who passed in A - total no. of students who passed for both A & B =50 - x
  similarly, no. of students who got pass only in B = 60 - x
  now, total no. students who got pass = 80
  80= (50 - x) +(60-x)+x
  then we'll get on solving, x=30
  
  students who passed in A only = 50 -x= 50-30=20
• 9 years agoHelpfull: Yes(19) No(2)
• 20 students fail in both subject
  80 students are remains
  60 out of 80 passed in B
  SO 80-60=20
  20 STUDENTS PASS IN subject A
• 9 years agoHelpfull: Yes(9) No(2)
• n(A∪B) = n(A) + n(B) - n(A∩B)
  n(A∪B) = 60 + 50 - 30 = 80
  So 80 passed in atleast one of the exams. 100 - 80 = 20 failed in both.
  Probability = 20/100 = 1/5
• 9 years agoHelpfull: Yes(3) No(6)
• Total no. Of pass students in any subject=80
  Pass in b =60
  So pass in a=20
• 9 years agoHelpfull: Yes(1) No(1)
• 100 attended
  20 failed in both. So 80 passed in both.
  Out of those 80 , 60 get passed in B.
  So simply 20 gets passed in Subject A
  Hope this helps.
  Thanks.
• 6 years agoHelpfull: Yes(1) No(1)
• 20 through venn diagram
• 9 years agoHelpfull: Yes(0) No(5)
• 20 the students passed in a only
• 9 years agoHelpfull: Yes(0) No(1)
• already number of studesnts passed subject a is given .then waht do mean by a only ?
  
• 8 years agoHelpfull: Yes(0) No(2)
• n(a) = 50; n(b) =60; n(AUB) = 100-20=80; ; n(anb) = ( 50 + 60) - 80 = 30
  Number of students who passed in A only = n(a)-n(anb) = 50 - 30 = 20
• 3 years agoHelpfull: Yes(0) No(0)
• 100-20 = 80
  60 out 0f 80 students pass in b
  so, 80-60 = 20
  20 pass in sub A
• 2 years agoHelpfull: Yes(0) No(0)