The following table and scatter plots display data for the

Chapter 5, Problem 44

(choose chapter or problem)

The following table and scatter plots display data for the number of fixed-line phone connections worldwide and the number of cell phone subscribers over the years 1985 1998. As indicated by the scatter plots, the number of cell phone subscribers is far less than the number of phone lines, but it is increasing at a faster rate. (a) Use the regression option on a graphing utility or spreadsheet to find a quadratic model y at2 bt c describing the number of phone lines over the period 19851998 (t 0 to t 13). Similarly, find an exponential model of the form y abt or y AeBt describing the number of cell phone subscribers. Then use the graphing utility to display the scatter plots and the two models in the same viewing rectangle. (b) By finding an appropriate viewing rectangle, make a projection for the year in which there would be as many cell phone subscribers as phone lines. G CYear t Phone lines subscriberst (t 0 4 1985) (millions) (millions)0 407 11 426 12 446 23 469 44 493 75 520 116 546 167 574 238 606 349 645 5510 691 9111 738 14212 788 21513 844 319Source: International Telecommunications Union data as reportedin Vital Signs 2000, Lester Brown et al. (New York:W. W. Norton & Co., 2000)