You should start by finding the correct price or quantity of something and its recent growth rate in percent. You can look on the Internet, in a book or in a periodical. For instance, you may find that the median house price in some area is $150,000, and it is growing at about 4% per year. Or, you might find that tuition in a state average is $8000 and is growing at 6% per year. Once you find your information, record where you found it, as the project requires a citation. For the remainder of the project, we will assume this rate of growth does not change. Then you will consider whether that rate of growth is realistic.