Question

Let C ( t ) be the number of US cell phone subscribers in millions in t years since 1995. A linear model for the data is F ( t ) = 18.997 t + 17.711 .
Use the model to predict the year in which the number of subscribers will 324 million

Answer 1

ANSWER

In 16 years time.

EXPLANATION.

If the number of subscribers is 324 million, then it means

$f(t)=324$

But we were given that,

$f(t)=18.997t+16.711$

This implies that,

$324=18.997t+16.711$

We now solve for t,

$324-16.711=18.997t$

$307.289=18.997t$

$\frac{307.289}{18.997}=t$

$16.17566=t$

That will be approximately in the 16th year.