
I used a website http://www.had2know.com/academics/regression-calculator-statistics-best-fit.html. It allowed you to input ordered pairs and then would give you four answers: Linear, Exponential, Power, and Logarithmic. The are other websites that have even more options.A teacher could get a lot of mileage out of this. Students could take guesses at which of the four would be best and which would be worst, and what the winning equation might look like. Enough suspense. The equations the website came up with are as follows:
Linear: y = 42877.1492x-209477.1429
Correlation: 0.6949
Exponential: y = 41.5145(1.9468^x)
Correlation: 0.9992
Power: y = 11.9805(x^3.5337)
Correlation: 0.9267
Logarithmic: y = -202534+180689.7131lnx
Correlation: 0.512
The winner? Judging by the correlations, the exponential equation, although the power equation wasn't bad. The others, fairly bad.
Students could graph the original 15 ordered pairs along with these four equations for some conformation.