Answer
The total garbage in pounds produced in the United States in one day is $1.38\times {{10}^{9}}$ pounds.
Work Step by Step
The total garbage in pounds produced in the United States in one day is equal to the product of the United States population and the garbage produced by each person every day.
$\begin{align}
& \left( 3.0\times {{10}^{8}} \right)4.6=3.0\times 4.6\times {{10}^{8}} \\
& =13.8\times {{10}^{8}} \\
& =1.38\times {{10}^{1}}\times {{10}^{8}} \\
& =1.38\times {{10}^{9}}
\end{align}$
Therefore, the total garbage in pounds produced in the United States in one day is $1.38\times {{10}^{9}}$ pounds.