SOLUTION: How many quarts of pure antifreeze must be added to 5 quarts of a 10​% antifreeze solution to obtain a 40​% antifreeze​ solution?
Question 1044620: How many quarts of pure antifreeze must be added to 5 quarts of a 10% antifreeze solution to obtain a 40% antifreeze solution? Found 3 solutions by addingup, ikleyn, Edwin McCravy:Answer by addingup(3677) (Show Source):
You can put this solution on YOUR website! Let x = amount of pure antifreeze required
Pure antifreeze is 100% = 1x
.10(5)+x = .40(x+5)
.5+x = .4x+2
.6x = 1.5
x = 2.5 gallons of pure antifreeze are needed
:
John
You can put this solution on YOUR website! How many quarts of pure antifreeze must be added to 5 quarts
of a 10% antifreeze solution to obtain a 40% antifreeze solution?
Here's another way to think of it:
The 5 quarts of 10% antifreeze contains (5)(0.10) = 0.5 quart of pure
antifreeze, (and the rest of the 5 quarts is 4.5 quarts of water,
which we aren't concerned with).
We are adding X quarts of pure antifreeze to the 0.5 quarts of pure
antifreeze (and water). So after pouring them together,
there will be X+0.5 quarts of pure antifreeze in the mixture. And
that will make 5+X quarts of liquid.
The equation is
Multiply both sides by (5+X)
Multiply through by 10 to clear the decimals.
Edwin
