The population of crocodiles in the swamp remains more or less constant, half males and half females?

Question

Each female crocodile lays 25 eggs over lifetime.
What percentage of eggs develope into mature crocodiles?

Answer 1

8% -- but see below.

To maintain equilibrium, each croc female will need to, on average, have two offspring that mature into adult croc, one male, one female.

Therefore, 2 out of 25 need to mature, or 8%.

But this has a trick to it. If the longevity of one sex greatly exceeds the other, then the answer is wrong. For example, if females lived twice as long once they reached maturity as male crocs, then to retain the balance, an adult female would, on average, have to 3 eggs mature, one female and two males, or 12%.

The bottom line is you could structure the population profile such that the minimum need to survive is 4% (all the males are virtually imortal and you just need female replacements), or 100% (the adult males tend to die off quickly and the reproductive rate is 4% female, 96% male).