Thread: Problem related to Population Growth

1. Problem related to Population Growth

I am having a test the day right after spring break and throughout this time i don't know where to look for help, so i hope someone can help me with this problem

Suppose that a certain population is modeled by the following Differential Equation: dP/dt = 2P(P/120-2)
For what values of P is decreasing? For what values of P is increasing?

I tried to solve the D.E. by setting all the P's on one side but that didnt seem to work at all

2. You don't actually have to find P(t), just see where dP/dt is negative (and where positive).

3. so do I just have to plug and chuck? or is there a easier way to find the exact solution?

the solution I got is: P is descreasing when 0<P<240
P is increasing when P>240

4. Correct

Not sure what your worry is - if you didn't do it by solving dP/dt = 0 = 2P(P/120-2) or else p^2 / 60 - 4p then try that