Chapter 1.3, Problem 13E

Landlines The percent of U.S. households with telephone landlines has decreased at a roughly linear rate, as shown by Che following table. Source: Centers for Disease Control and Prevention.

Year	Percent of Households
2005	89.7
2006	84.1
2007	81.9
2008	77.9
2009	73.5
2010	68.2
2011	63.8
2012	59.6

(a) Find the equation of the least squares line, letting x equal the number of years since 2000.

(b) Based on your answer to part (a), at approximately what rate is the percent of households with landlines decreasing per year?

(c) Use your result from part (a) to predict the percent of households with landlines in the year 2015.

(d) If this trend continues linearly, in what year will the percent of households with landlines first dip below 40%?

(e) Find and interpret the correlation coefficient.