Question

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?

• A. 50
• B. 100
• C. 200
• D. 4000

Answer 1

Answer: (C)

200

Answer 2

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