答案 1/49
设A中有水1/8 a , B中有水2/8 a , C中有水3/8 a ,酒精X
一开始 A B C
1/8 a+X 2/8 a 3/8 a
2/8 a 4/8 a+X
4/8 a+1/2X 2/8 a+1/2X
1/2x / (4/8 a+1/2X )=2/100
x=1/49a
答案 1/49
设A中有水1/8 a , B中有水2/8 a , C中有水3/8 a ,酒精X
一开始 A B C
1/8 a+X 2/8 a 3/8 a
2/8 a 4/8 a+X
4/8 a+1/2X 2/8 a+1/2X
1/2x / (4/8 a+1/2X )=2/100
x=1/49a