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The penguins at New York zoo are planning an audacious escape attempt to the wild. It is essential for success of the operation that only fit penguins participate, whilst ill birds must remain in the zoo. Of the 100 penguins planning their escape, 17 test seropositive for Salmonella madigastica and 83 seronegative. The chief penguin demands further molecular testing which reveals 1/17 of the seropositive penguins does NOT have Salmonellosis, whilst 7/83 of the seronegative penguins HAVE Salmonellosis.
(In this exercise we assume the molecular test is a gold standard for Salmonella in penguins).