According to data from the u. s. department of education, the average cost y of tuition and fees at public four-year institutions in
year x is approximated by the equation
y -0.024x*- 0.87x? + 9.67°+97.2x + 2196
where x = 0 corresponds to 1990. if this model continues to be accurate, during what year will tuition and fees reach $4000