# Organisms and Populations

N_{t}=N_{0}e^{rt}

where as :

N_{t} = Population density after time t;

N_{0} = Population density after time 0;

r = intrinsic rate of natural increase;

e = base of natural log.

$${dN \over dt} = rN ({ k-N \over k}) $$

Where as:

N = Population density at time t;

r = Intrinsic rate of nutual increase;

k = Carring capicty

$${N _{t+1}} ={ N _t} +[{(B + I) - (D + E)} ] $$

Where as:

N_{t+1} = Population density at time t+1;

N_{t} = Population density at time t;

B = Birth

D = Death

I = Immigration

E = Emmigration