Question

How do you find how many quarts of 4% butterfat milk and 1% butterfat milk should be mixed to yield 60 quarts of 2% butterfat milk?

Answer 1

`color(blue)20` quarts of `4%` and `color(blue)40` quarts of `1%` will give `60` quarts of `2%`

Explanation:

Let `x` be the number of quarts of `4%` required.
This implies the number of quarts of `1%` required will be `60-x`

The total butter fact will be
`color(white)("XXX")4/100 * x +1/100 * (60-x)=2/100 * 60`

`color(white)("XXX")rarr 4x+60-x= 2 *60`

`color(white)("XXX")rarr 3x+60=120`

`color(white)("XXX")3x=60`

`color(white)("XXX")x=20`

So `20` quarts of `4%` are needed plus `(60-20)=40` quarts of `1%`