In an effort to determine the size of an animal population, 100 animals are captured and...

In an effort to determine the size of an animal population, 100 animals are captured and tagged. Some time later, another 50 animals are captured, and it is found that 20 of them are tagged. How would you estimate the population size? What assumptions about the capture/recapture process do you need to make? (See Example I of Section 1.4.2.)

Reference

Capture/Recapture Method

The so-called capture/recapture method is sometimes used to estimate the size of a wildlife population. Suppose that 10 animals are captured, tagged, and released. On a later occasion, 20 animals are captured, and it is found that 4 of them are tagged. How large is the population?