Symbiosis National Aptitude Test SNAP 2015 Paper

Question : 30 of 150

Marks: +1, -0

A man and his wife appear in an interview for twovacancies in the same post. The probability of husband’s selection is (1/7) and the probability of wife’s selection is (1/5). What is the probability that only one of them is selected?

4/5
2/7
8/15
4/7

Validate

Solution:

Let A = Event that the husband is selected
and B = Event that the wife is selected.
Then, P(A) =

1/7

and P (B) =

1/5

∴

P(A↖{-})

(1-1/7)

6/7

and

P(B↖{-})

(1-1/5)

4/5

∴ Required probability = P [(A and not B) or (B and not A)]
= P [(A and

B↖{-}

) or (B and

A↖{-}

)]
= P (A and

B↖{-}

) + P (B and

A↖{-}

)
=

P(A).P(B↖{-})+P(B).P(A↖{-})

(1/7×4/5)+(1/5×6/7)

{10}/{35}

2/7

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