2. In 2009, the world population was 6.8 billion. The exponential growth rate was 1.13% per year. So the following could be used as a model for the growth of the world's population: P=6.8e00113, where P is world population in billions, represents the number of years past 2009. (2009 would be represented by 1=0.) a. Estimate the population of the world in 2018 using this model. b. Using the internet, find an approximation for the world population in 2018. What is the difference between the estimate from the internet and the answer in part (a)? c. Using algebraic methods and the model given, estimate the year when the world population will be 9 billion.