Answer
$43872$ Subscribers.
$(1.05)^{m}$
Work Step by Step
We use an exponential function $y=a\cdot b^x$.
Number of years $x=1994-1985=9 \;years$.
The cell phone subscribers in $1994$: $=y$.
The initial cell phone subscribers: $a=285$
The growth factor: $b=1+.75=1.75$.
Substitute all values into the function.
$\Rightarrow y=285\cdot (1.75)^9$
Simplify.
$\Rightarrow y=43872$.
Hence, $43872$
The expression for monthly cell phone subscription increase is
$=(1.75)^x$
$=(1.75)^{\frac{12x}{12}}$
$=(1.75^{\frac{1}{12}})^{12x}$
$=(1.05)^{12x}$
Let $12x=m$
$=(1.05)^{m}$.
