In a mark-recapture study to estimate the size of a rodent population, researchers catch and mark 30 individuals. Two days later, they again capture a number of rodents and find that 20% of the individuals are marked. Assuming no births, deaths, or migrations, what is the estimated size of the population?

Answer: The estimated size of the population is 150

Explanation: For the Mark-Recapture method, there is a formula that can be used:

N = (M * C) / R

where:

N = estimated number of individuals in the population

M = number of individuals captured and arked

C = total number captured the second time (with and without a mark)

R = number of individuals ecaptured (those with a mark)

So with this formula we can calculate an estimation of the population of rodents. Because there is no number of rodents captured the second time given, we will assume 30 was caught again, making the 20% found marked being 6. We calculate it as:

N = (M * C) / R

:N = (30 * 30) / 6

:N = 900/6

:N = 150 estimated rodents in the population