The population of the world in 1987 was 5 billion and the annual growth rate was estimated at 2 percent per year.

Question

The population of the world in 1987 was 5 billion and the annual growth rate was estimated at 2 percent per year. Assuming that the world population follows an exponential growth model, find the projected world population in 1990.

  billion

Answer 1

The formula for exponential growth is:

f(x) = a(1 + r)^x

where:

a is the initial amount,

r is the growth rate, and

x is the number of time intervals

We know that our initial amount is 5 billion (a = 5 [billion]), the growth rate is 2% (r = 0.02), and the time interval is yearly (x = 1990 – 1987 = 3).

Plugging this into our equation:

f(x) = 5(1 + 0.02)³

= 5 * 1.02³

= 5.30604 billion

= 5,306,040,000