The Average Product of Capital of Producing 2,991 Units of Output

Multiple Choice

The average product of capital of producing 2,991 units of output (find point B) in the table below is:
$$\begin{array}{l}\text { Production Function far God } \mathbf { X }\\\begin{array} { l l l l l } L ^ { * } & K & Q & M _ { K } = ( \Delta Q / \Delta K ) & \begin{array} { l } \mathbf { M P } _ { K } = ( Q / K ) \\\text { Mverage }\end{array} \\\text { Labor } & \text { Capital } & \text { Output } & \begin{array} { l } \text { Product of } \\\text { Capital }\end{array} & \begin{array} { l } \text { Product of } \\\text { Capital }\end{array} \\9 & 0 & 0 & - & - \\9 & 10 & 57 & 5.7 & 5.70 \\9 & 20 & 324 & 26.7 & 16.20 \\9 & 30 & 657 & 33.3 & \mathbf { B } \\9 & 40 & 1,072 & 41.5 & 26.80 \\9 & 50 & 1,524 & 45.2 & 30.48 \\9 & 60 & 1,976 & 45.2 & 32.93 \\9 & 70 & 2,391 & 41.5 & 34.16 \\9 & 80 & 2,724 & 33.3 & 34.05 \\9 & 90 & 2,991 & \mathbf { A } & 33.23 \\9 & 100 & 3,048 & 5.7 & 30.48 \\9 & 110 & 3,016 & - 3.2 & 27.42 \\9 & 120 & 2,945 & - 7.1 & 24.54\end{array}\end{array}$$

A) 11.1.
B) 21.9.
C) 37.
D) 73.