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Numerical Ability
Permutation and Combination
A father purchased dress for his 3 daughters. The dresses are of same color but diff size and they are kept in dark room. what is probability that all the 3 will not choose their own dress?
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- the arrangement will follow this way =>first girl will choose wrong dress AND second girl will wrong dress AND the third girl will choose wrong dress.
since there are three dresses so .
=>first girl will choose wrong = 1-(1/3) = 2/3
now two dress are left
=>second girl will choose wrong out of two dress left => 1-(1/2) =1/2
now third girl will chose in only one way=1
so required probability= 2/3*1/2*1
=1/3 (ans) - 9 years agoHelpfull: Yes(19) No(0)
- total number of dresses =3
probabilty of choosing the right dress=(1/3)(1/3)(1/3)= 1/27
not choosing the right dress = 1-(1/27)= 26/27 - 9 years agoHelpfull: Yes(7) No(7)
- This is a case of de-arrangements = Dn=n!(1/2!−1/3!+1/4!−....)
So number of ways that none of them chooses their own dress = D3=3!(1/2!−1/3!)=2
So probability = 2/3!=1/3
:) - 9 years agoHelpfull: Yes(6) No(1)
- ans: 2/6 = 1/3
as their are total 6 possibilities of selecting dress (abc, acb, bac, bca, cab, cba) for (g1g2g3) daughter
suppose a dress for g1 b dress for g2 and c dress for g3 are correct choices
then out of 6 possibilities only (bca and cab) 4 t and 5 th outcomes are for all the 3 will not choose their own dress. - 9 years agoHelpfull: Yes(1) No(0)
- 8/27(2/3*2/3*2/3)
- 9 years agoHelpfull: Yes(0) No(1)
- $ $ $ -> dress
! ! ! -> girl 1st girl pick either 2nd or 3rd
2nd girl pick either 1st or 3rd
3nd girl pick either 1st or 2nd each girl can pick 2 dress ,then 3 girls pick 6 dress. so no.of way 2/6=1/3 - 9 years agoHelpfull: Yes(0) No(0)
- This is a case of de-arrangements = Dn=n!(12!−13!+14!−....)
So number of ways that none of them chooses their own dress = D3=3!(12!−13!)=2
So probability = 23!=13
- 9 years agoHelpfull: Yes(0) No(0)
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