$2000$ kg$/$h of soybean meal containing $45\%$ by weight edible oil is to be treated in a multiple stage counter current leaching equipment using $3000$ kg$/$h of n$-$hexane containing $\%$ oil by weight. The insoluble solids retain $1$ kg solution per kg of its weight in each stage, How many ideal stages are required if $90\%$ recovery of the oil is desired.