SOLUTION: Alfalfa meal contains 2% nitrogen by weight. Bat guano contains 10% nitrogen by weight. How many pounds of each should be mixed together to make 7 pounds of fertilizer that is 8%

Question 301849: Alfalfa meal contains 2% nitrogen by weight. Bat guano contains 10% nitrogen by weight. How many pounds of each should be mixed together to make 7 pounds of fertilizer that is 8% nitrogen?
Answer by stanbon(75887) (Show Source): You can put this solution on YOUR website!
Alfalfa meal contains 2% nitrogen by weight. Bat guano contains 10% nitrogen by weight. How many pounds of each should be mixed together to make 7 pounds of fertilizer that is 8% nitrogen?
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Let "A" be the weight of Alfalfa meal.
Let "B" be the weight of Bat guano.
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Equation:
Weight Equation: A + B = 7
nitrogen + nitrogen = nitrogen
0.02A + 0.10(7-A) = 0.08(7)
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Multiply thru by 100 and solve for "A":
2A + 10*7 - 10A = 8*7
-8A = -3*7
A = 3/8 lbs (amt of Alfalfa meal needed in the mixture)
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B = 7-(3/8) = (56/8)-(3/8) = 53/8 lbs (amt of Bat guano needed in the mix)
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Cheers,
Stan H.
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