A travel research firm has reported average occupancy and room rates for hotels in 26 U.S. hotel markets. The data are also in file XR17007. For y = average room rate (dollars) and x = average occupancy rate (percent), fit a second-order polynomial model to the data and determine the percentage of the variation in average room rates that is explained by the model. Given the nature of these variables, comment on causation possibilities that might be present.