Latest CAT Aptitude Question SOLUTION: 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 c

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(#M40019228) CAT question Keep an EYE

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?

Asked In CAT MohanRaj (11 years ago)

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Deepashree  (11 years ago)

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

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venkatesh  (11 years ago)

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

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