Chance Of Balls
Two drawing, each of 3 balls, are made from a bag containing 5 white and 8 black balls, the balls not being replaced before the second trial : If The Probability of drawing 3 white in first and 3 blacks in second draw be A/B .
Then Find A+B
Note A and B are co - primes
The answer is 436.
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1 solution
The probability of picking 3 white balls in the first draw is C(5,3)/C(13,3)
now 3 white balls are removed from the bag.
The probability of picking 3 black balls in the second draw is C(8,3)/C(10,3)
Hence the result is ( C(5,3) C(8,3) )/ ( C(13,3) C(10,3) ) =7/429
a=7 n b=429
a+b=436