Pre-treated sunflower seeds containing 27.5% oil, 67.5% solids and 5% hexane as a weight percent are extracted using 1000 kg of hexane-oil mixture containing 2% oil at each stage. At the end of the process, it is foreseen that there will be a maximum of 5% oil in the downstream leaving the last stage. For 2000 kg input current; a) Calculate the minimum amount of solvent to be used. b) Find the theoretical number of steps required for this separation. The amount of oil carried by the solution in the downstream and the amount of solution retained by the inert solid are given in the table.

\begin{tabular}{|c|c|} \hline kg ya / kg czelti & kg czelti / kg kat madde \\ \hline 0.0 & 0.42 \\ \hline 0.2 & 0.50 \\ \hline 0.4 & 0.55 \\ \hline 0.6 & 0.60 \\ \hline 0.8 & 0.65 \\ \hline \end{tabular}