math for the expanding population

Mon, 2 Jan 1995 15:22:00 PST

Bonnie Blackwell provides the basic demographic equation for a growing
population. The following may be a useful addition to what she presented:

Let D be the number of years for a populaiton to double in size,
let r be the net growth rate (expressed as a proportion).

Then D = ln2/r, where ln2 is the natural log of 2.

ln2 = (approximtely) 0.695

So with a net growth rate of 2.78% the doubling time is 0.695/.0278= 25 years.
D. Read