The formulas of organisms population in biology

Organisms and Populations

Exponential Growth Equation

Nt=N0ert where as :
Nt = Population density after time t;
N0 = Population density after time 0;
r = intrinsic rate of natural increase;
e = base of natural log.

Logistic Growth Equation

$${dN \over dt} = rN ({ k-N \over k}) $$ Where as:
N = Population density at time t;
r = Intrinsic rate of nutual increase;
k = Carring capicty

Population Density

$${N _{t+1}} ={ N _t} +[{(B + I) - (D + E)} ] $$ Where as:
Nt+1 = Population density at time t+1;
Nt = Population density at time t;
B = Birth
D = Death
I = Immigration
E = Emmigration