Answer:
The company's WACC is 9.14%
Explanation:
cost of preferred stock 
= (dividend on preferred stock)/(current market price)
= [$100*4%]/$72
= 5.56%
total finance = debt + equity + preferred stock
                      = (8,000*$1,060) + (310,000*$57) + (15,000*$72)
                      = $8,480,000 + $17,670,000 + $1,080,000
                       = $27,230,000
weight of debt = debt/total finance
                          = $8,480,000/$27,230,000
                          = 0.31
weight on equity = equity/total finace
                              = $1.080.000/$27,230,000
                              = 0.04
WACC 
= (weight of debt*after tax cost of debt) + (weight on equity*cost of equity) 
= (0.31*0.0393) + (0.65-0.1185) + (0.04*0.0556)
= 9.14%
Therefore, The company's WACC is 9.14%