(1)甲公司股票价值=1×(P/F,12%,1)+1×(1+10%)×(P/F,12%,2)+1×(1+10%)×(1+5%)/(12%-5%)×(P/F,12%,2)=1×0.8929+1×(1+10%)×0.7972+1×(1+10%)×(1+5%)/(12%-5%)×0.7972=14.92(元)由于甲公司股票的价值低于目前的股价,所以,不值得投资。(2)假设投资收益率为r,则:1×(P/F,r,1)+1×(1+10%)×(P/F,r,2)+1×(1+10%)×(1+5%)/(r-5%)×(P/F,r,2)=20当r=10%时:1×(P/F,10%,1)+1×(1+10%)×(P/F,10%,2)+1×(1+10%)×(1+5%)/(10%-5%)×(P/F,10%,2)=20.91当r=12%时:1×(P/F,12%,1)+1×(1+10%)×(P/F,12%,2)+1×(1+10%)×(1+5%)/(12%-5%)×(P/F,12%,2)=14.92所以有:(20.91-20)/(20.91-14.92)=(10%-r)/(10%-12%)解得:r=10.30%由于甲公司股票的投资收益率低于必要报酬率,所以,不值得投资。(3)假设债券投资的收益率为s,则:1050=1000×8%×(P/A,s,3)+1000×(P/F,s,3)即1050=80×(P/A,s,3)+1000×(P/F,s,3)当s=6%时80×(P/A,6%,3)+1000×(P/F,6%,3)=80×2.6730+1000×0.8396=1053.44当s=7%时80×(P/A,7%,3)+1000×(P/F,7%,3)=80×2.6243+1000×0.8163=1026.24所以有:(1053.44-1050)/(1053.44-1026.24)=(6%-s)/(6%-7%)解得:s=6.13%由于乙公司债券的投资收益率高于必要报酬率(即市场利率),所以,值得购买。(4)债券价值=80×(P/A,6%,4)+1000×(P/F,6%,4)=80×3.4651+1000×0.7921=1069.31(元)由于债券价格高于价值,所以,不值得购买。