Question

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?

Answer 1

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`