可以详细解释一下吗？看了其他解释没看懂

NO.PZ2018113001000003问题如下 A $100 million pension funwith 80% stoan20% bon The beta of equity portion is 1.2 anthe ration of bonportion is 5.0. In orr to aust the allocation to 60% stoan40% bon Calculate the number of stoinx futures neeto buy. Baseon the following information: The stoinx value is 1,200, multiplier is $250, the beta is 0.95 The priof bonfutures contrais $105,300 with impliemofieration of 6.5. A.-88B.-84C.-95 B is correct.考点用futures contra调整组合的头寸解析现需要将股票头寸从80%降至60%，即需要将20%*100,000,000=$20,000,000的股票的beta调整为0（转成cash）需要的stoinx futures contract数量为Nf=(βT−βSβf)(Sf)=(0.00−1.200.95)($20,000,0001,200×$250)=−84.21(−84rounN_f=(\frac{\beta_T-\beta_S}{\beta_f})(\frSf)=(\frac{0.00-1.20}{0.95})(\frac{\$20,000,000}{1,200\times\$250})=-84.21(-84rounNf​=(βf​βT​−βS​​)(fS​)=(0.950.00−1.20​)(1,200×$250$20,000,000​)=−84.21(−84roun负号代表卖出，即需要卖出84份股票期货合约, 对应的也就是买入（-84）份合约，选（注意，本题中问的是需要的股指期货合约的份数，因此关于债券的信息是用不到的） 我总是搞不清f应该用哪个数，题目里的远期合约价格105300在什么时候会用到？

NO.PZ2018113001000003 问题如下 A $100 million pension funwith 80% stoan20% bon The beta of equity portion is 1.2 anthe ration of bonportion is 5.0. In orr to aust the allocation to 60% stoan40% bon Calculate the number of stoinx futures neeto buy. Baseon the following information: The stoinx value is 1,200, multiplier is $250, the beta is 0.95 The priof bonfutures contrais $105,300 with impliemofieration of 6.5. A.-88 B.-84 C.-95 B is correct.考点用futures contra调整组合的头寸解析现需要将股票头寸从80%降至60%，即需要将20%*100,000,000=$20,000,000的股票的beta调整为0（转成cash）需要的stoinx futures contract数量为Nf=(βT−βSβf)(Sf)=(0.00−1.200.95)($20,000,0001,200×$250)=−84.21(−84rounN_f=(\frac{\beta_T-\beta_S}{\beta_f})(\frSf)=(\frac{0.00-1.20}{0.95})(\frac{\$20,000,000}{1,200\times\$250})=-84.21(-84rounNf​=(βf​βT​−βS​​)(fS​)=(0.950.00−1.20​)(1,200×$250$20,000,000​)=−84.21(−84roun负号代表卖出，即需要卖出84份股票期货合约, 对应的也就是买入（-84）份合约，选（注意，本题中问的是需要的股指期货合约的份数，因此关于债券的信息是用不到的） The priof bonfutures contrais $105,300 with impliemofieration of 6.5.这个条件用不上对吗？为什么这里用beta算不用ration算呢/？

NO.PZ2018113001000003问题如下 A $100 million pension funwith 80% stoan20% bon The beta of equity portion is 1.2 anthe ration of bonportion is 5.0. In orr to aust the allocation to 60% stoan40% bon Calculate the number of stoinx futures neeto buy. Baseon the following information: The stoinx value is 1,200, multiplier is $250, the beta is 0.95 The priof bonfutures contrais $105,300 with impliemofieration of 6.5. A.-88B.-84C.-95 B is correct.考点用futures contra调整组合的头寸解析现需要将股票头寸从80%降至60%，即需要将20%*100,000,000=$20,000,000的股票的beta调整为0（转成cash）需要的stoinx futures contract数量为Nf=(βT−βSβf)(Sf)=(0.00−1.200.95)($20,000,0001,200×$250)=−84.21(−84rounN_f=(\frac{\beta_T-\beta_S}{\beta_f})(\frSf)=(\frac{0.00-1.20}{0.95})(\frac{\$20,000,000}{1,200\times\$250})=-84.21(-84rounNf​=(βf​βT​−βS​​)(fS​)=(0.950.00−1.20​)(1,200×$250$20,000,000​)=−84.21(−84roun负号代表卖出，即需要卖出84份股票期货合约, 对应的也就是买入（-84）份合约，选（注意，本题中问的是需要的股指期货合约的份数，因此关于债券的信息是用不到的） 在一些具体数据上不知道哪个ration用在谁的BPV上，可以展示一下具体的过程吗？谢谢

NO.PZ2018113001000003 问题如下 A $100 million pension funwith 80% stoan20% bon The beta of equity portion is 1.2 anthe ration of bonportion is 5.0. In orr to aust the allocation to 60% stoan40% bon the number of stoinx futures neeto sell is? Baseon the following information: ŸThe stoinx value is 1,200, multiplier is $250, the beta is 0.95 ŸThe priof bonfutures contrais $105,300 with impliemofieration of 6.5. A.-88 B.-84 C.-95 B is correct.考点用futures contra调整组合的头寸解析现需要将股票头寸从80%降至60%，即需要将20%*100,000,000=$20,000,000的股票的beta调整为0（转成cash）需要的stoinx futures contract数量为Nf=(βT−βSβf)(Sf)=(0.00−1.200.95)($20,000,0001,200×$250)=−84.21(−84rounN_f=(\frac{\beta_T-\beta_S}{\beta_f})(\frSf)=(\frac{0.00-1.20}{0.95})(\frac{\$20,000,000}{1,200\times\$250})=-84.21(-84rounNf​=(βf​βT​−βS​​)(fS​)=(0.950.00−1.20​)(1,200×$250$20,000,000​)=−84.21(−84roun因此，需要卖出84份股票期货合约。 老师好 怎么问法是 用40MM （=20M +20M）来做？像课上例题 3.1（截图)中把 50M +50M = 100M 来转？