MBA
Exam
Numerical Ability
Probability
A bag contains 5 balls and it is not known how many of them are blue in colour. If 2 balls are drawn and found to be blue, then the probability that all the balls in the bag are blue is 1) 1/4 2) 1/2 3) 2/5 4) none of these
Read Solution (Total 1)
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- P(2/5) =(2C2)/(5C2) =1/10
P(3/5) = 3C2/5C2 =3/10
P(4/5) = 4C2/5C2 = 6/10
P(5/5) =5C2/5C2 = 1
Hence required conditional probability = p(5/5)/{p(2/5)+...p(5/5)} = 1/(1/10+3/10+6/10+10/10)
= 1/2. - 11 years agoHelpfull: Yes(0) No(0)
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