Will the new iPhone sales be huge?

Apple just announced their new, 10^th anniversary, iPhones, the iPhone 8 and the iPhone X.  These phones will soon be in stores, the iPhone 8 comes out on September 22, 2017. The iPhone X is available as of November 3rd.  What will their record sales be like this time?  How many iPhones will they sell? In this activity students explore past iPhone sales by year and try to predict how many iPhone 7's, 8's, and X's will be sold during the 2017 sales year as well as in the future. Younger students can investigate the data through a bar graph, while older students can use a scatter plot and even use equations to model sales growth.