[IB Biology Ecology Reviews]

19. 40 leeches are caught from a pond, marked and released. A week later, 100 leeches are caught from the same pond, of which 10 are marked. Using the equation for the Lincoln Index seen above, calculate the estimated number of leeches in the pond.

A) 4

B) 40

C) 400 (40 X 100 divided by 10)

D) 4000

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Slichter