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Bag ' A ' contains 9 green and 1 red ball, Bag ' B ' contains 10 balls all of them being green, 9 balls are drawn randomly from Bag ' A ' and put into bag ' B ', and then 9 balls are randomly transferred from bag ' B ' to bag ' A '. If p q (in its lowest form) is the chance that the red ball is still there in the bag ' A ' then the value of (q-p) is equal to

Correct answer

9

Step-by-step solution

p q =1- ^9 C ₈ ^1 C ₁ ¹⁰ C ₉ ¹⁸ C ₉ ¹⁹ C ₉ =1- 9 19 = 10 19 So q-p=19-10=9

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