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AIIMS 2001
Exam
AIIMS
Year
2001
Subject
Zoology
Chapter
Organisms and Populations

AIIMS 2001 · Zoology · Organisms and Populations

Some students, during a study, caught, marked and released 80...

Some students, during a study, caught, marked and released 80 fishes in a pond. Later 100 fishes were caught at random. Among these 40 were found to be marked. What is the approximate number of fishes in the pond?

Options

  1. A50
  2. B100
  3. C200
  4. D4000

Correct answer

C. 200

Step-by-step solution

According to Petersons Mark and Recapture Method, the population (P) is given by P=m(r+u) / r where m=m= number of marked fishes r=r= number of marked fishes recaptured u=u= number of unmarked fishes captured Here,m=80r=40u=(100−40)=60P=m(r+u)/r=80(40+60)40P=200\begin{aligned}m & =80 \\ r & =40 \\ u & =(100-40) \\ & =60 \\ P & =\mathrm{m}(\mathrm{r}+\mathrm{u})/ \mathrm{r}\\ & =\frac{80(40+60)}{40}\\ P & =200 \end{aligned}
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