Electrochemical machining operations are performed with tungsten as the tool, and copper and aluminum as two different workpiece materials. Properties of copper and aluminum are given in the table below.
$\begin{array}{|c|c|} \hline
\text{Material} & \text{Atomic mass (amu)} & \text{Valency} & \text{Density} (g/cm^{3}) \\ \hline
\text{Copper} & \text{63} & \text{2} & \text{9} \\ \hline
\text{Aluminum} & \text{27} & \text{3} & \text{2.7} \\ \hline
\end{array}$
Ignore overpotentials, and assume that current efficiency is $100\%$ for both the workpiece materials. Under identical conditions, if the material removal rate $\text{(MRR)}$ of copper is $100\; mg/s$, the $\text{MRR}$ of aluminum will be _______________________ $\text{mg/s}$ (round-off to two decimal places)
