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A box contains a white balls and b black balls and besides the box lies a large pile of black balls. Two balls chosen at random are taken out of the box. If they are of the of the same colour , a black ball form the pile is put into the box. The procedure is repeated until the last two balls are remove dfrom the box and one last ball is put in. What is the probability that this last ball is white provided (1) a is even (2) a is odd?



 A box contains a white balls and b black balls and besides the box lies a large pile of black balls. Two balls chosen at random are taken out of the box. If they are of the of the same colour , a black ball form the pile is put into the box. The procedure is repeated until the last two balls are remove dfrom the box and one last ball is put in. What is the probability that this last ball is white provided (1) a is even (2) a is odd?



Grade:12

1 Answers

Saurabh Koranglekar
askIITians Faculty 10336 Points
2 years ago
Dear student

Ways of selection
(a+b) C 2

if the same color

ie both white or both black
new b’ = b-1
or b’ = b

new selection
(a+b’) C 2

same is done for another round

and required answer can be calculated

Regadrs



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