SOLUTION: A chemist needs 90 milliliters of a 20% solution but only has only 4% and 40% solutions available. Find how many milliliters of each that should be mixed to get the desired solutio
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Question 911585: A chemist needs 90 milliliters of a 20% solution but only has only 4% and 40% solutions available. Find how many milliliters of each that should be mixed to get the desired solution. Answer by richwmiller(17219) (Show Source):
You can put this solution on YOUR website! We need a total of 90 mL at 20%
We want to know how many mL at 4% to mix with 40%
a+b=90,
0.04*a+0.4*b=0.2*90
a=90-b
0.04*(90-b)+0.4*b=18
3.6-0.04b+0.4*b=18
0.36*b=14.4
b=40
a=90-b
a=50 mL at 4%
b=40 mL at 40%
check
0.04*50+0.4*40=0.2*90
2+16=18
18=18
ok
codemx1
