老师，请看下我的理解是否正确，谢谢。

NO.PZ2016082404000019

XYZ Co. is a gold producer and will sell 10,000 ounces of gold in three months at the prevailing market price at that time. The standard deviation of the change in the price of gold over a three-month period is 3.6%. In order to hedge its price exposure, XYZ Co. decides to use gold futures to hedge. The contract size of each gold futures contract is 10 ounces. The standard deviation of the gold futures price is 4.2%. The correlation between quarterly changes in the futures price and the spot price of gold is 0.86. To hedge its price exposure, how many futures contracts should XYZ Co. go long or short?

选项：

  Short 632 contracts

  Short 737 contracts

  Long 632 contracts

  Long 737 contracts

解释：

ANSWER: B

XYZ will incur a loss if the price of gold falls, so should short futures as a hedge. The optimal hedge ratio is $\rho\frac{\sigma_S}{\sigma_F}=0.86\times\frac{3.6}{4.2}=0.737.$. Taking into account the size of the position, the number of contracts to sell is $0.737\times\frac{10,000}{10}=737.$

737我求出来了，现在是回答long和short的问题有些障碍。

1.我的理解是：因为要sell，所以担心价格下跌，所以short；担心价格上涨，long；是吗？

2.老师讲过Beta大于0就long，是不是这个只能用于股指期数，不是在这里用的。这里的h和beta的计算公式很相似，不知道能不能串用。