To measure the population density of monarch butterflies occupying a particular park, 100 butterflies are captured, marked with
a small dot on a wing, and then released. The next day, another 100 butterflies are captured, including the recapture of 20 marked butterflies. One would estimate the population to be
Given merely 40 butterflies were marked, assumed that there were multiple captures of both marked and unmarked butterflies, that the butterflies caught in traps were on the loose to be caught again. There are two mathematical solutions for this, both yielding the same answer which is 100.
• First, to each marked butterfly was taken twice (40 marked X2 = 80 captured) then of the unmarked butterflies the 120 captured must relate to 60 actual butterflies. In which 40 + 60 = 100.
• Secondly, by means of ratios in which 80/200 = 40/X. In this case X also = 100 that will result to the estimated size of the population of wilson park is 100.
