$A$ group of individuals living in a particular geographical area at a particular time is called:

Scientific study of human population is called

The different age groups in a population are classified by:

$A$ biologist studied the population of rats in a barn. He found that the average natality was $250$, average mortality $240$, immigration $20$ and emigration $30$. The net increase in population is

If natality rate is parallel to mortality rate,then the population:

If $8$ Drosophila in a laboratory population of $80$ died during a week, the death rate in the population is