Latest TCS Aptitude Question SOLUTION: there are two boxes,one containing 39 red balls & the other containing 26 green balls.you are allowed to move the balls b/w the boxes so that when you choose a box random & a ball

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(#M40010918) TCS question Keep an EYE

there are two boxes,one containing 39 red balls & the other containing 26 green balls.you are allowed to move the balls b/w the boxes so that when you choose a box random & a ball at random from the chosen box,the probability of getting a red ball is maximized.this maximum probability is
a)60 b)50 c)80 d)30

Asked In TCS Prateek Parihar (12 years ago)

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Sanket Kumar  (12 years ago)

Well Keep a single red ball in 1 box and move 38 red balls to the other

1st box = 1R
2nd box = 38R + 26G

p(red) = 1/2 * 1 + 1/2 * 38/64 ≈ 0.8

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Chockkalingam S  (12 years ago)

the probability of getting a red ball should be maximized so we will keep 1 red ball in the first box and transfer remaining 38 red balls to other box which has green. The reason for doing this only this combination will make the probability of getting red ball is maximum (i.e) 1.
In the question its mentioned that first we have to choose a box at random.
So 2 boxes are there, probability of selecting a bag is 1/2
Probability of getting red ball from first box is 1
Probability of getting green ball from second box is 38/64
So (1/2)*1 for first box and (1/2)*(38/64) for box 2
answer is (1/2)*1 + ((1/2)*(38/64) which is approximately 0.8

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SHANU MAHAJAN  (12 years ago)

chockkalingam s pls write correctly 38/64 is probability of getting red not green.

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