Question

Julius is studying populations of robins in the local area. He counts 12

robins and marks 7 of them. Later, he recaptures 3. About how large is the local robin population?

Answer 1

Well, he recaptured 3 out of the 7 he marked. We can presume that the other 5 are gone. The population would be 8 robins, because 4 of the robins Julius marked were not recaptured. Therefore, the population is around 8-10 robins.