The music business is evolving into a digital marketplace.

Chapter 7, Problem 8

(choose chapter or problem)

The music business is evolving into a digital marketplace. The bar graph shows that from 2004 through 2009, CD album sales declined, while digital track sales grew. 1400 1200 1000 800 600 Sales (millions) 400 Sales of Albums and Digital Tracks in the United States 2009 293 1237 Year 2004 2007 511 868 770 200 142 Digital track sales CD album sales Source : RIAA a. In 2004, 142 million digital tracks were sold. For the period shown by the graph, this has increased at an average rate of 219 million digital tracks per year. Write a function that models the sale of digital tracks, y, in millions, x years after 2004. b. The function 95x + y = 770models the number of albums sold, y, in millions, x years after 2004. Use this model and the model you obtained in part (a) to determine when digital track sales caught up with album sales. How many digital tracks and how many albums were sold in that year?