一道finance的题目 求各位大神关注

Question

Suppose that Intel currently is selling at $20 per share. You buy 1000 shares by using
$15,000 of your own money (investment equity) and borrowing the remainder of the
purchase price from your broker. The rate on the margin loan is 8%. You are
considering two possibilities:
Possibility 1: In one year, the price of Intel is 25.
Possibility 2: In one year, the price of Intel is 15.
a. For each case described above, what is the value of total assets, liabilities, and total
investment equity in your portfolio in one year? What is the net return on equity?
b. For each case described above, find the net return on equity using portfolio weights.
Show work. Your answers to part (a) and (b) should be the same. Show your work.

c. Suppose you expect Intel to return 10% with a standard deviation of 0.18. What is
the expected return and standard deviation of your portfolio?

Answer 1

　　我只写一下第一种可能，第二种可能是重复的。
　　a.按照题目中的投资 你会得到一个如下的资产负债表
　　期初资产：1000*20＄ （Intel） 期末资产：1000*25＄（value of total asset）=25000＄
　　期初负债：5000＄ 期末负债：5000*（1+8%）＄（liabilities）=5400＄
　　期初权益：资产—负债=15000＄ 期末权益=期末资产-期末负债=19600＄
　　期末回报=期末权益—期初权益
　　=19600＄-15000＄=4600＄（net return on equity） 组合回报率=4600÷15000=0.3066
　　value of total investment equity是你用自己的钱购买的证券（750股）的期末价值，所以等于750*25＄。

　　b.组合权重：资产权重20000÷15000=1.33
　　负债权重-5000÷15000=-0.33
　　资产回报率=（25000-20000）÷20000=0.25
　　负债回报率=（5400-5000)÷5000=0.08
　　组合的净回报率=1.33*资产回报率-0.33*负债回报率
　　=1.33*0.25-0.33*0.08=0.3066
　　检验：4600÷15000=0.3066

　　c.标准差0.18的单位是什么？如果是＄的话。
　　那么组合的标准差=0.18*1000
　　组合的预期收益为 4600+10%*25*1000