Population Equations

If P is the population at the start of the year, Y is the number of young that are born and survive, and D is the number of cheetahs that die in a year, then the population at the end of the year is given by this expression:

P + Y - D

If P is the population at the start of the year and Y is the number of young that are born and survive in that year, then the rate of reproduction is given by this expression:

Y/P

If no animals arrive from the outside of the region being studied, and no animals leave to the outside, then the population at the beginning of one year (say, 1996) is related to the population at the beginning of the next year (say, 1997), by this equation (where R is the rate of reproduction and A is the rate of attrition):

P1997 = P1996 + P1996 (R - A)

Use principles of algebra to rearrange and solve one variable equations.

Subject: Mathematics
Topics: Algebra, Expressions and Equations
Grades: 6 - 12
Knowledge and Skills:
- Can evaluate expressions by substituting values for variables
- Can simplify expressions using correct order of operations
- Can do basic operations on both sides of an equation in such a way as to preserve the equality

Download Teacher Guide: Population Equations (PDF)
Download Student Lesson: Population Equations (PDF)

CheetahsCheetahs:

To help save an endangered species like the cheetah, you must start by understanding its behavior. Only the brave need apply for this job, however, because this kind of biological study is up close and personal.
Running time 2:08 minutes.

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