A student has to appear for an objective test .Probabiloty he knows the answer is 3/4 and probability that he giesses the answer is 1/4.If probability that the student guesses the anwer and it is correct is 1/4, one question is chosen at random and the answer is correct .Find the probability that he guesses the answer.
sweety70:
which class r u ? based on that I could answer
class 11
plz help me with this mam
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E1 = probability of knowing ans
E2 = probability of giessesing ans
P(E1)=3/4 p(E2)= 1/4
if A= probability that answer is correct
Then probability that the student guesses the answer and it is correct is = 1/4 =p(A/E1)
so the probability thatone question is chosen at random and the answer is correct =
p(E1/A)= p(A/E1)×p(E1)/p(A/E1)×p(E1) +p(A/E2)×p(E2)
= 1/4×1/4/1/4×1/4+1/4×3/4
1/4
E2 = probability of giessesing ans
P(E1)=3/4 p(E2)= 1/4
if A= probability that answer is correct
Then probability that the student guesses the answer and it is correct is = 1/4 =p(A/E1)
so the probability thatone question is chosen at random and the answer is correct =
p(E1/A)= p(A/E1)×p(E1)/p(A/E1)×p(E1) +p(A/E2)×p(E2)
= 1/4×1/4/1/4×1/4+1/4×3/4
1/4
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