In the year 2008 Apple sold 11 million iPhones. Over the next few years, annual sales increased by an average of 55%, which we will model using a geometric sequence with r = 1.55
Use the geometric summation formula Sn = a1 (1-r^n) / 1 - r, to estimate the total number of iPhones sold in the eight years spanning 2008 and 2015. Give your answer in millions of phones, rounded to one decimal place.
___________ million phones
