1) The document describes how to create a scatter plot of year versus number of teams data on a graphing calculator. It involves inputting the data into L1 and L2 and turning on the stat plot.
2) It then explains how to determine the best fit line or curve using regression models. This involves turning on the diagnostics and testing different regression models like linear, quadratic, cubic etc.
3) The quadratic model was found to best fit the data with an equation of N(t) = -0.003t^2 + 0.621t + 11.003, which models the number of teams (N) over time (t) in years using the regression analysis.