Answer
a. $(2004, 180)$. $2004$, $180$ million
b. year $2004$. $180$ million
c. very well.
Work Step by Step
a. Based on the given graph, the intersection point can be found to be around $(2004, 180)$. This means that in 2004, the number of cellphone and land-line customers are the same, with about 180 millions of customers for each.
b. Based on the first models, we have $ y = 198-4.3x $ for the number of
land-line customers, and for the second model
$y = 19.8x + 98$. Let $198-4.3x = 19.8x + 98$
we have $24.1x=100$ which gives $x=4.15\approx4$ or year $2004$. At $x=4.15$, we have $y=198-4.3(4.15)\approx180$ million for each model.
c. We can see that the model results from part-(b) fit the data from part-(a) very well.
