In 2011, the world's population reached 7 billion and had been increasing at a rate of 1.2% per year for some time. Assume that this growth rate remains constant when answering the questions below (a) Write a formula to model the world's population as a function of the number of years since 2011.
(b) Suppose we have additional information and know that the world's population in 2017 reached 7.61 ton. Based on this new information, what was the annual growth rate between 2011 and 2017 (arming is was constant)? Give your answer as a percent to 1 decimal place
(c) Now write a formula for the world's population as a function of time since 2011 using our new information about the growth rate.