Proofs of a certain book were read independently by two proofreaders who found, respectively, k and k misprints; k misprints were found by both. Give a reasonable estimate of the unknown number, n, of misprints in the proofs. (Assume that proofreading corresponds to Bernoulli trials in which the two proofreaders have, respectively, probabilities p and p2 of catching a mis print. Use the law of large numbers.) Note: The problem describes in simple terms an experimental setup used by Rutherford for the count of scintillations.