#1809 · Probability · Conditional probability
Six balls of unknown colours
In a bag there are six balls of unknown colours; three balls are drawn and found to be black; find the chance that no black ball is left in the bag.
H. S. Hall & S. R. Knight, Higher Algebra (1891) · Ch. XXXII. Probability, Examples XXXII.d, No. 2
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Checked against the answer in H. S. Hall & S. R. Knight, Higher Algebra (1891).