2、20000-(20700-20500)= 19800

3. The profit per ton is 200 yuan, and the supply is (20700-20500)*5*400=400000 yuan.

2. 1, a, buy Yuanyue, sell Jin Yue contract arbitrage b, sell Yuanyue, buy near-term contract arbitrage c, no arbitrage.

2. A {(2210-2100)+(2120-2220)} *1hand = 10 profit.

B {(2100-2210)+(2220-2120)} | = *1hand =- 10 loss.

Third, a typical book example, refer to the formula, see the "Futures Market Tutorial", there must be.

The hedging of the first question is feasible, and there are practical examples in the textbook.