In 2014, the world's population reached 7.17 billion 1 and was increasing at a rate of 1.1% per year. assume that this growth rate remains constant. (in fact, the growth rate has decreased since 2008.) (a) enter a formula for the world population, p, (in billions) as a function of the number of years, t, since 2014.

The formula is:

P= (population in 2014) x (1+r) ^n

where: r= rate

           n=number of years

and to solve using the formula above :

Population = 7.17 * 1.011^(2018-2014)  

Population = 7.17 * 1.011^4

Population = 7.49 Billion (Rounded)  

The question is 1.1% per year

Example:  

Lets say you start at 1000  

1.1% of 1000 is 11  

Making the next population after 1000 be 1000+11 = 1011  

Given initial population=Po=7.17 billion

and rate=r=1.1

The population is increasing exponentially

P=poe^rt

P=7.17e^0.011*t

After 6 years the population will be is 7.66 billion

Hence population in 2020 will be 7.66 billion.