#1812 · Probability · Conditional probability

Purse of unknown coins

A purse contains $n$ coins of unknown value; a coin drawn at random is found to be a sovereign; what is the chance that it is the only sovereign in the bag?

~10 minAnswer checked instantlyBayes theoreminduction and combinatorics

H. S. Hall & S. R. Knight, Higher Algebra (1891) · Ch. XXXII. Probability, Examples XXXII.d, No. 5

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Checked against the answer in H. S. Hall & S. R. Knight, Higher Algebra (1891).