Answer
Initial amount $a=700$ Rate of decay $r=0.5\%$ At $t=3,w(3)\approx 689.6$.
Work Step by Step
The given expression is
$\Rightarrow w(t)=700(0.995)^t$
$\Rightarrow w(t)=700(1-0.005)^t$
The standard form of an exponential decay function is $y=a(1-r)^t$
Initial amount $a=700$
Rate of decay $r=0.005=0.5\%$
Substitute $3$ for $t$.
$\Rightarrow w(3)=700(0.995)^3$
Evaluate the power.
$\Rightarrow w(3)=700(0.985074875)$
Simplify.
$\Rightarrow w(3)=689.5524125$
Round to the nearest tenth.
$\Rightarrow w(3)\approx 689.6$.
