algebra word problem

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 1991. Answer is in billions.

Answer 1

P(t) = P₀·( 1 + rate)t

• P(t) = population in  year t after 1987
• P₀ = population in 1987 = 5 billion
• rate = growth rate = 2% = 0.02
• t = years since 1987 = 1991-1987 = 4

 

P(t) = 5·(1.02)⁴

 

Use your calculator to compute the answer.