SOLUTION: Milk that has 5% butterfat is mixed with milk that has 2% butterfat. How much of each is needed to obtain 120 gallons of milk that has 4% butterfat?

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Question 1179803: Milk that has 5% butterfat is mixed with milk that has 2% butterfat. How much of each is needed to
obtain 120 gallons of milk that has 4% butterfat?
Found 2 solutions by josgarithmetic, greenestamps:
Answer by josgarithmetic(39617) (Show Source):
You can put this solution on YOUR website!
The number values given are very simple.
4% fat wanted is closer to 5% than to 2%. The interval from 2 to 5 is made of three equal parts. The 120 gallons is composed of 40 gallons and 80 gallons. The mixture only needs 40 gallons of the 2% butterfat milk.

CHECK:

Answer by greenestamps(13200) (Show Source):
You can put this solution on YOUR website!

The solution method used by the other tutor is very good (and faster and easier than the standard formal algebraic method). But in my opinion the presentation of the method could be better.

Here is the same solution using different wording.

The target 4% is 2/3 of the way from 2% to 5%; that means 2/3 of the mixture must be the milk with 5% butterfat.
Since 120 gallons of the 4% milk are to be produced, 80 gallons must be the 5% milk and the other 40 gallons must be the 2% milk.