J.K. Rowling’s popular Harry Potter books have tended to become thicker with each new edition. The publication year and page count for U.S. editions for the first seven books were as shown on the next page. The data are also in file XR17059. Using year codes so that x = 1 corresponds to 1998, the year the first book was published, fit a third-order polynomial model to the data and estimate the page count for a Harry Potter book published in 2015.