Lets make fun of Obama while he is still relevant.

[Mikebert]

Warren Dew Wrote:d(population)/dt / population > 0 (percentage population increases as old people have retired but not died yet)
 
d(GDP/population)/dt = population * d(GDP)/dt + GDP * d(population)/dt

Using more compact notation you are saying:
 
d(GDP/N)dt = N * dGDP/dt + GDP dN/dt
 
this is the differentiation of the product of GDP and N, done correctly you would have
 
d[GDP * (1/N)]/dt = (1/N) dGDP/dt - GDP (1/N)^2 (dN/dt)
 
I'm still confused