Mona asked in Science & MathematicsBiology · 10 years ago

Population problem - biology?

In a study, 5000 flies were captured and marked with a powder and released.

The next day, 515 flies were captured and 21 of them had marks

how many flies are in the population?

I don't know how to do it. Does it have to do with percentage?

2 Answers

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  • 10 years ago
    Favorite Answer

    N=MC/R

    where

    N = Estimate of total population size

    M = Total number of animals captured and marked on the first visit

    C = Total number of animals captured on the second visit

    R = Number of animals captured on the first visit that were then recaptured on the second visit

    so, in your case

    M=5000

    C=515

    R=21

    Easy math gives you

    N=(5000*515)/21

    N=122,619 flies in that population

  • 10 years ago

    Yes. Set up equivalent proportions for the size of the population / number marked:

    515 in captured population / 21 marked = x in total population / 5000 marked. Then just solve for x → (5000/21) x 515 = x =122,619.

    Source(s): Forty years teaching Biology, currently teaching College Math Refresher course
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