In 1999 the worlds population reached 6 billion an was increasing at a rate of 1.3% per year. Assume that this growth rate remains constant, how do you write a formula for the world population (in billions) as a function of the number of years since 1999?

1 Answer
Jul 31, 2016

Population
#=6(1+0.013)^n billions#
Where #n# is the number of #years# since #1999#

Explanation:

Since #1.3%# can be written as #0.013#
we can write the equation
Population
#=6(1+0.013)^n billions#
Where #n# is the number of #years# since #1999#
Assuming we want to know the population in the year #2016#
from the above equation #n# that is the number of #years# since #1999#
So
#n#
#=2016-1999#
#=17# Years
Population in the #year 2016# as per the formula is
#=6(1+0.013)^n billions#
#=6(1.013)^17 billions#
#=6(1.25) billions#
#=7.5 billions#