the results of the examination in two papers A and B for 20 candidates were as follows.
8 candidates passed in A
7 candidates passed in B
8 candidates failed in both
out of these candidates one is selected.what is the probability he passed in both these papers?

• Candidates failed only in A : 4
  Candidates failed only in B : 5
  Candidates failed in Both : 8
  So candidates failed in (A OR B OR Both) : 17
  So candidates passed in both : 3
  Probability is 3/20
• 10 years agoHelpfull: Yes(5) No(0)
• two subjects a,b and 20 students
  given that num of stu's passed in a is pass(a)=8
  num of stu's passed in a is pass(b)=7
  and num of stu's failed in both sub's is fail(a&b) = 8
  so from these pass(a)+pass(b)-pass(a&b)+fail(a&b) = 20
  num of stud's pass in both subj's are pass(a&b) = 8+8+7-20 = 3
  rhe probability of one student will be pass in both the sub is 3c1/20c1 = 3/20
  
• 10 years agoHelpfull: Yes(2) No(0)