help with table 5 and finding concentration was in your stock unknown

\begin{tabular}{|l|l|l|} \hline StandardTube# & OD-from spec & Adjusted OD \\ \hline 1 & 2.2143 & 2.117667 \\ \hline 2 & 1.712 & 1.615333 \\ \hline 3 & 1.2933 & 1.196667 \\ \hline 4 & 1.072667 & 0.976 \\ \hline 5 & 0.75433 & 0.6576667 \\ \hline 6 & 0.459667 & 0.363 \\ \hline 7 & 0.29 & 0.19333 \\ \hline 8 & 0.135 & 0.3633 \\ \hline 9 & 0.9667 & 0 \\ \hline UK sample & OD & Adjusted OD \\ \hline Undiluted & 3.222666667 & 2.836666667 \\ \hline 1:50 & 2.154333333 & 2.154333333 \\ \hline 1:100 & 1.614 & 1.614 \\ \hline 1:250 & 0.386 & 0.386 \\ \hline \end{tabular} \begin{tabular}{|c|c|c|} \hline Sample ID & Water & Unknown Stock \\ \hline 1:50 & 490l & 10l \\ \hline 1:100 & 495l & 5l \\ \hline 1:250 & 498l & 2l \\ \hline \end{tabular} Table \# 5 - CALCULATIONS \begin{tabular}{|l|l|l|} \hline StandardTube# & OD-from spec & Adjusted OD \\ \hline 1 & 2.2143 & 2.117667 \\ \hline 2 & 1.712 & 1.615333 \\ \hline 3 & 1.2933 & 1.196667 \\ \hline 4 & 1.072667 & 0.976 \\ \hline 5 & 0.75433 & 0.6576667 \\ \hline 6 & 0.459667 & 0.363 \\ \hline 7 & 0.29 & 0.19333 \\ \hline 8 & 0.135 & 0.3633 \\ \hline 9 & 0.9667 & 0 \\ \hline UK sample & OD & Adjusted OD \\ \hline Undiluted & 3.222666667 & 2.836666667 \\ \hline 1:50 & 2.154333333 & 2.154333333 \\ \hline 1:100 & 1.614 & 1.614 \\ \hline 1:250 & 0.386 & 0.386 \\ \hline \end{tabular} \begin{tabular}{|c|c|c|} \hline Sample ID & Water & Unknown Stock \\ \hline 1:50 & 490l & 10l \\ \hline 1:100 & 495l & 5l \\ \hline 1:250 & 498l & 2l \\ \hline \end{tabular} Table \# 5 - CALCULATIONS