债券成本=15000*10%/(15000*(1-1%))*0.75=0.0757575757576 优先股=12%/(1-2%)=0.122448979592 普通股=12%/(1-4%)+4%=0.165 各自占比 15000/40000=0.375 5000/40000=0.125 20000/40000=0.5 综合资本成本=0.0758*0.375+0.1224*0.125+0.165*0.5=0.126225