$11.$ An alkylation unit produces $40,000$ barrels of high$-$octane gasoline per day by reacting $30,000$ barrels of isobutane with an excess of propylene. If the conversion efficiency of propylene to gasoline is $75\%,$ what is the yield of gasoline?

$12.$ A refinery processes $200,000$ barrels of crude oil per day with an average sulfur content of $1\mathrm{.}5\%.$ If the desulfurization unit can remove $80\%$ of the sulfur during processing, how many kilograms of sulfur are removed daily?