Percentage question

Question

Two horse feed products were used by a livestock company. Blue nag feed was 17% protein. Green pasture was 25% protein. How much of each was used to make bags of 60 pounds that contained 20% protein?

Answer 1

Because we know that the total weight of the feed is 60 pounds, we can call the weight of one of the feeds x and the other 60-x.  Let's say x is the blue nag feed.  Then...

Protein in blue nag = 0.17x

Protein in green pasture = 0.25 (60-x) = 15 - 0.25x

Total protein = (0.20) 60 = 12 

 

0.17x + 15 - 0.25x = 12

 

-0.08x = -3

x = 37.5

 

So a mixture of 37.5 pounds of blue nag and 22.5 (60 - 37.5) pounds of green pasture will yield 60 pounds of 20% protein feed.