Question

Which equation represents a population of 250 animals that decreases at an annual rate of 21% ?

A. p = 250(1.21)
B. p = 250(1.79)
C. p= 250(0.79)
D. p=250(0.21)

Answer 1

Answer: Choice C.  p = 250(0.79)^t

Work Shown:

p = a*b^t

p = a*(1+r)^t

p = 250*(1+(-0.21))^t

p = 250(0.79)^t

Note that r = -0.21 is negative to indicate we have exponential decay.