B. the model an = 395n + 5419 describes the cost of tuition and fees at public colleges in academic year n, where n = 1 corresponds to the school year ending in 2007, n = 2 to the school year ending in 2008, and so on.
a. use this model and the formula for sn to find the total cost of tuition and fees at public colleges for a four-year period from the school year ending in 2007 through the school year ending in 2010