Let us pretend that today was in Oct. 2019. The crude oil futures contract would mature one year later, Oct. 2020; Each contract consists of 1,000 barrels, with "Multiplier" = 1000.00; Each contract requires $4,180.00 as the initial margin for traders to long (ie., "buy on margin") or short, with "Margin" = 4180.00; No matter you long or short this commodity today, assume that the price can be settled at $50.68 per barrel, with "Last Price" = 50.68; Your specific brokerage firm will decide the interest rate for cash. Currently the borrowing rate is assumed to be APR = 2.5% per year, while the deposit rate is negligible (APR=0%). And crude oil, of course, pays no interest or dividend at all.

Question C: The brokerage firm requires all buyers and sellers must keep the maintenance margin to be at least 2% of the traded commodity value. In other words, traders' equity amount must be no less than 2% of the market value of 1,000 barrels of oil, otherwise they will receive margin call (to urge for more money or to foreclose account). What price amount of oil will begin to trigger a margin call to you? And what price amount of oil will begin to trigger a margin call to Leo?

Please note that a margin call could happen anytime soon, even long before the interest on borrowed cash becomes due.