Modeling with Exponential Functions

Each of the problems below is a link. If you click on the problem, it will take you to a YouTube video of a full, step-by-step solution for the problem. You may try these problems as practice and use the videos to check your answer, or you can just watch the videos to see more worked-out example problems.

In 2000 the population of the world was 6.1 billion and the relative rate of growth was 1.4%. Estimate the population of the world in 2050 using this rate, and estimate it using a relative growth rate of 1.0%. Compare your results.
A certain breed of rabbit was introduced onto a small island about 8 years ago. The current rabbit population is 4100, with a relative growth rate of 55% per year. What was the initial size of the rabbit population? Estimate the population 12 years from now.
A culture initially contains 1500 bacteria and doubles every 30 minutes. Find a function that models the number of bacteria n(t) after t minutes. Find the number of bacteria after 2 hours. After how many minutes will the culture contain 4000 bacteria?