SOLUTION: An agronomist has 4 % nitrogen fertilizer and 20 % nitrogen fertilizer. He needs to get 500 pounds of 14 % nitrogen fertilizer. Determine the number of pounds of each he needs to m

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Question 994963: An agronomist has 4 % nitrogen fertilizer and 20 % nitrogen fertilizer. He needs to get 500 pounds of 14 % nitrogen fertilizer. Determine the number of pounds of each he needs to mix
Answer by vleith(2983) About Me  (Show Source):
You can put this solution on YOUR website!
let x be the number of pounds of 4%. That means there are 500-x pounds of 20%
0.14+%2A+500+=+0.04%2Ax+%2B+0.20%2A%28500-x%29
70+=+0.04x+%2B+100+-+0.2x
-30+=+-0.16x
187.5+=+x
So there are 187.5 pounds of 4%
Which leaves 312.5 pounds of 20%
As a quick check, realize that you added more 20% than you did 4%. Since 14% is closer to 20% than it is to 4%, adding more of the 20% makes sense right!