Question

Assume that the growth rate of a population of ants is proportional to the size of the population at each instant of time. Suppose 100 ants are present initially and 230 are present after 3 days.
a. Write a differential equation that models the population of the ants.

b. Solve the differential equation with the initial conditions.

c. What is the population of the ants after 14 days?

Answer 1

(1/A)  dA/dt=  C where A is the population of ants and C is a constant
ln(A) = C*t + C1 where C1 is another constant that comes out of integration and t is time in days.
Plugging in: at t=0, A= 100 so C1 = ln(100) = 4.605
at t=3, A=230 so ln(230) = 3*C +4.605 so C = 0.278
Final equation:
ln(A) = 0.278t + 4.605
or:
A = exp(0.278t + 4.605)
After 14 days, A = exp(0.278*14 + 4.605) = 4875.2