Here Is the Distribution of Workers a Restaurant Keeps on Staff

Multiple Choice

Here is the distribution of workers a restaurant keeps on staff during a 1-hour shift.
$\begin{array}{|l|l|l|l|l|}\hline \text {probability} & 0.10 & 0.25 & 0.55 & 0.10 \\\hline \text { \# of workers} & 3 & 4 & 5 & 6 \\\hline\end{array}$

If the workers are paid $10/hour, what is the expected long-term cost of a 1-hour shift?

A) none of these
B) $180
C) $46.50
D) $4.65
E) $45