A.11%+20%+15%=46% B.(11%+20%+15%)÷3=15.3% C.[(1000+1400+1200)/(1000/111%+1400/120%+1200/115%)]-100%=15.7% D.(111%+120%+115%)÷3=115.3%
A.110.51% B.104.76% C.115.01% D.108.23%
A.減少l5% B.增加15 C.不變化 D.判斷不出