Question

How much water must be added to 12 L of a 40% solution of alcohol to obtain a 30% solution?

A. .5 L
B. 5 L
C. .4 L
D. 4 L

Answer 1

almost identical to the last one

Answer 2

The total volume should be 12l*(40%/30%)=16l
So how much water must be added?

Answer 3

@emmat9795 Please close a problem only when you finish with it. Thanks :)

Answer 4

you have \(.4\times 12=4.8\) L of alcohol to begin with
if you add say \(x\) liters of water you will still have 4.8 L of alcohol but now you will have
\(12+x\) liters of liquid
you want this to be 30% alcohol, so set \(4.8=0.3(12+x)\) and solve for \(x\)

Answer 5

whatever @ParthKohli