Chapter 1.3, Problem 26E

(A)

To determine

The slope of each model depicted by the data given in the table below. The table represents the average annual telephone expenditures (in dollars) per consumer unit on residential phone service and cellular phone service.

$\begin{array}{|ccc|}\hline \text{Year}& \text{Residential service }\left(\$\right)& \text{Cellular service }\left(\$\right)\\ 2001& 686& 210\\ 2003& 620& 316\\ 2005& 570& 455\\ 2007& 482& 608\\ 2009& 434& 712\\ \hline\end{array}$

The scatter plot and linear regression model is given below:

(B)

To determine

To determine :The annual residential and cellular expenditure in $2020$, with the help of linear model $y=-32.1x+719$ for residential service and model $y=64.8x+136$ for cellular service.

(C)

To determine

To determine :Whether the linear regression models give reasonable predictions for the year $2025$. The given linear model for the residential service is $y=-32.1x+719$ and the cellular service is $y=64.8x+136$. Also, explain the predictions.