Consider the oil futures market where each contract is for one barrel of oil. The oil is physically delivered to holders of the contract on the expiration date. Suppose the April oil futures contract expires tomorrow and the May oil futures contract expires 30 days later. The price today for the April contract has turned negative and is trading at -$38 while the price for the May contract is +$22. Using an arbitrage argument, derive the average storage cost per day for storing a barrel of oil until the May expiration. You may assume interest rates are zero and there are no other costs associated with holding oil. This actually did happen in April 2020