<PRE><B>Question 229261</B>
How much water must be added to 16 liters of a 30% solution to get a solution that is 22% acid?
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16 liters of 30% = 4.8 liters of acid.
Add water until that 4.8 liters is 22% of the total.
4.8:22::x:100
22x = 480
x = 240/11 liters = the total volume of 22%
240/11 - 16 = 64/11 liters of water to add
64/11 = ~ 5.818 liters of water 
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Note: If you add 16 liters of water, the %age would be 1/2, or 15%, so the answer looks good.</PRE>