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

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Solution:

Net increase in population can be calculated by a formula: (B+I) - (D+E) where in B refers to Birth rate/Natality, I refers to Immigration, D refers to Death rate/Mortality and E refers to Emigration. Therefore net increase for the population of rats in barn is (250+20) - (240+30), thereby 270-270. Hence net increase is zero

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