The Following Table Shows the Total Output Per Hour Produced

Multiple Choice

The following table shows the total output per hour produced in a factory at various levels of employment of labor. The firm sells each unit of output at $2 and each worker is paid a wage of $12.
Table 5-1
$\begin{array} { | c | c | } \hline \begin{array} { c } \text { Nurnber of } \\\text { workers }\end{array} & \text { Total output } \\\hline 1 & 8 \\\hline 2 & 18 \\\hline 3 & 30 \\\hline 4 & 41 \\\hline 5 & 50 \\\hline 6 & 55 \\\hline 7 & 59 \\\hline 8 & 61 \\\hline 9 & 62 \\\hline\end{array}$
-Refer to Table 5-1. What is the marginal revenue product of the 4th worker?

A) $82
B) $20.50
C) $22
D) $18
E) None of these answers is correct.