[問題]濃度

[Grace]

Solution A is 20 percent liquid K and 80 percent water and solution B is 10 percent liquid K and 90 percent water. If 2 gallons of solution A and 3 gallaons of solution B are porued into the same container, how many gallons of liquid K should be added into the container to obtain a solution that is 50 percent liquid K and 50 percent water?

A. 1.2
B. 2.4
C. 3.6
D. 4.8
E. 6.0


Ans: C

How to cope with this problem? Please help~ :P

[Behemoth]

a溶液中--0.4gallon的k + 1.6gallon的water
b溶液中--0.3gallon的k + 2.7gallon的water

所以加起來---0.7gallon的k + 4.3gallon的水

4.3-0.7=3.6

[Grace]

原來這題目這樣簡單...繞很久就是繞不出來....
謝謝 B 桑囉...