75%的酒精量 = 95%酒精量 = 500ml * 95% = 475ml
95%酒精含水量 = 500ml * (1 - 95%) = 25ml
75%的酒精总量 = 75%的酒精量 / 75% = 475ml * 100 / 75 = 633ml + 1/3ml
75%的酒精含水量 = 633ml + 1/3ml - 475ml = 158ml + 1/3ml
放水量 = 75%的酒精含水量 - 95%酒精含水量 = 158ml + 1/3ml - 25ml = 133ml + 1/3ml
500毫升百分之95酒精稀释成75%酒精需要加水500*(95%-75%)/75%=400/3克≈133.34克水。
500x95%=475
475÷75%=624
624-500=124毫升
我用算术方法解答。