Answer
Initial amount $a=240$
Rate of decay $r=0.25=25\%$
At $t=3,g(3)\approx101.3$.
Work Step by Step
The given expression is
$\Rightarrow g(t)=240(0.75)^t$
$\Rightarrow g(t)=240(1-0.25)^t$
The standard form of an exponential decay function is
$y=a(1-r)^t$
Initial amount $a=240$
Rate of decay $r=0.25=25\%$
Substitute $3$ for $t$.
$\Rightarrow g(3)=240(0.75)^3$
Evaluate the power.
$\Rightarrow g(3)=240(0.421875)$
Simplify.
$\Rightarrow g(3)=101.25$
Round to the nearest tenth.
$\Rightarrow g(3)\approx101.3$.
