Probability Practice Test 1

Question : 33 of 40

Marks: +1, -0

A man is known to speak truth 3 out of 4 times. He throws a die and reports that it is a six, the probability that it is actually a six is

$3/8$
$1/5$
$3/5$
None of these

Validate

Solution:

Let A denote the event that a six occurs and B the event that the man reports that it is a six. Then the probability that it is actually a six is given by

P(A/B)={P(A ∩B)}/{P(B)}

Now,

{P(A ∩B)}=1/6 . 3/4 =1/8

P(B)=P(A∩B )+P(\ov A ∩\ov B)

=1/6 . 3/4+5/6 . 1/4 =1/3

P(A/B)={1/8}/{1/3}-3/8

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