SOLUTION: Question: Whole milk is 4% butterfat. How much skim milk with 0% butterfat should be added to 32 ounces of whole milk to obtain a mixture that is 2.5% butterfat. I tried doing

Question 908023: Question: Whole milk is 4% butterfat. How much skim milk with 0% butterfat should be added to 32 ounces of whole milk to obtain a mixture that is 2.5% butterfat.
I tried doing this and got 19.2 ounces but Im not sure if that is right because I did it a different way than the way i was taught it in class. I didnt make very good notes just wrote down the examples as we did them so I don't know if I did it the right way.
Thank You
Found 2 solutions by josgarithmetic, richwmiller:
Answer by josgarithmetic(39617) (Show Source): You can put this solution on YOUR website!
Good instruction for this type of mixture problem is here:

http://www.algebra.com/my/Two-Part-Mixture-with-one-material-quantity-unknown.lesson?content_action=show_dev

That should take care of any difficulties or misunderstandings.
Answer by richwmiller(17219) (Show Source): You can put this solution on YOUR website!
We have 32 oz of 4% milk fat
We want to add some 0% milk fat to make 2.5% milk fat
0*x+0.04*32=0.025(32+x)
0*x+1.28=0.8+0.025x
0x-0.025x=0.8-1.28
-0.025x=-0.48
x=19.2 oz at 0% (0.0) is added to 32 oz at 4%(1.28) to make 2.5% of 51.2 oz(1.28)
check
0*19.2+0.04*32=0.025(32+19.2)
0.0+1.28=0.025(51.2)
1.28=1.28
ok

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