SOLUTION: pure acid is to be added to a 10%acid solution to obtain 90l of 89% solution . what amounts of each should be used?

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Question 665032: pure acid is to be added to a 10%acid solution to obtain 90l of 89% solution . what amounts of each should be used?
Answer by vleith(2983) About Me  (Show Source):
You can put this solution on YOUR website!
Let the amount of pure acid be given by x. Then if the total volume is 90 liters, the amount of 10% acid is given by (90-x). Plug that in and solve
100%x + 10%(90-x) = 89%(90)
x+%2B+0.1%2890-x%29+=+0.89+%2A+90
x+%2B+9+-+0.1x+=+80.1
0.9x+=+71.1
x+=+79 so there must be 11 liters of 10% to start with.
And remember .... add acid to water, just like you oughta (and not the other way around)