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22 Mar 2010 14:48:26 IST
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A bag contains 4 balls. Two balls are picked up and found to be white. Find the probability that all the balls in the bag were white.
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22 Mar 2010 14:49:47 IST
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plz explain wid procedure.....rates assured for each attempt....
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22 Mar 2010 14:56:10 IST
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heloooooooo.........c'mon guys...ansr it plzzzz
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22 Mar 2010 15:00:20 IST
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hey dis qus in board s was wrong every 1 will get 6 marks for dis for free
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22 Mar 2010 15:00:42 IST
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r u sure?
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22 Mar 2010 15:04:28 IST
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three cases arise : 2 white (eventE1) 3 white (E2) 4 white (E3) each of these events hve equal prob.=1/3 let the event of withdrawing 2 white balls be A now P(A/E1)=2C2/4C2 P(A/E2)=3C2/4C2 P(A/E3)=4C2/4C2 now apply bayes theorem P(E3/A)= (P(E3)*P(A/E3)) / P(E3)P(A/E3) + P(E2)P(A/E2) + P(E1)P(A/E1) THE ANS IS 3/5
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22 Mar 2010 15:05:33 IST
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i don think that this a wrong question.......correct me in the above solution if it is so...
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22 Mar 2010 15:21:27 IST
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I don't think the question is wrong..................... I did it this way (M not sure about the answer)...................... The three cases are : {2 white balls, 3 white balls, 4 white balls} No of ways of having 2 white balls = 4C2 No of ways of having three balls white = 4C3 No of ways of having all balls white = 1 Hence, Probability of all balls white = 1/1+4C2+4C3 = 1/11
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Common sense is not very common. --- Voltaire
Man is born free, but is everywhere in chains.-------Jean Jacques Rosseau
The rule of SATAN is inevitable~~~~~~transmigrator
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22 Mar 2010 15:35:09 IST
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pata nahin yaar kya ho raha hai koi kuch keh raha hai koi kuch........4 no wale integration ke question 6 no walon se jyada lengthy the
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22 Mar 2010 15:55:54 IST
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3/5 yaar superman is correct
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22 Mar 2010 15:57:00 IST
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chalo koi to mila:)
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22 Mar 2010 16:02:17 IST
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Supermaan is correct .........aisa mujhe bhi lagta hai
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Common sense is not very common. --- Voltaire
Man is born free, but is everywhere in chains.-------Jean Jacques Rosseau
The rule of SATAN is inevitable~~~~~~transmigrator
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22 Mar 2010 16:31:00 IST
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yes,answer is 0.6.......
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22 Mar 2010 17:05:45 IST
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question is wrong n it was jugde by teachers of my n other schools stupid
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22 Mar 2010 17:07:49 IST
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n there r 2 6 marks qus were wrong in set 1 so every 1 will get 12 marks who attempt it
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22 Mar 2010 19:39:20 IST
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The question is totally correct. Here's the solution. Let Ei denote the evet that the bag contains i white balls and so (4 - i) balls of any other colour(s). Let A denote the event that the 2 balls drawn at random are white. P(Ei) = 1/5 (i =0,1,2,3,4) P(A/Ei) =0 for i = 0,1 P(A/Ei) = iC2/4C2 for i>2 Now by total probability rule, P(A) = summation i from 0 to 4 P(Ei) P(A/Ei) = (1/5)(1/4C2)(2C2 + 3C2 + 4C2) P(A) = (1/5)(1/6) (1 + 3 + 6) = 1/3 By the Bayes' rule P(E4/A) = P(E4) P(A/E4) / P(A) = (1/5) (1) / (1/3) = 3/5 = 0.6 (Ans)............
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22 Mar 2010 20:07:05 IST
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hey guys, let me tell u wat i think two balls are already picked up and they are white is confirmed so,,,, we have to calculate probablity for just remainning two balls, now we have to know the probablity of the event-> the ball is white. there is no information about that,it is true the question is incomplete.the black t-shirt guy was right i think this question is not bounded properly. there should be added some thing like half of the times the ball is white or there may diffrent 12 colored balls
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22 Mar 2010 20:15:24 IST
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i m sorry deepak is correct
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22 Mar 2010 20:15:59 IST
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i m sorry deepak is correct
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22 Mar 2010 20:16:10 IST
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i m sorry deepak is correct
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