SOLUTION: The meat department in a grocery store purchased 800 lb of hamburger that is 90% lean beef. How many lbs of hamburger that is 75% lean must be mixed with this 90% lean mix to produ

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Question 1041593: The meat department in a grocery store purchased 800 lb of hamburger that is 90% lean beef. How many lbs of hamburger that is 75% lean must be mixed with this 90% lean mix to produce hamburger that is 85% lean beef?
Found 2 solutions by josmiceli, stanbon:
Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
Note that fat is the part that is not lean
+.1%2A800+=+80+ pounds of fat in 800 pounds of meat
Let +x+ = pounds of hamburger that is 25% fat
that needs to be added
+.25x+ = pounds of fat in 25% fat hamburger
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Notice I switched from lean to fat in each case
( that way I get smaller numbers )
+%28+80+%2B+.25x+%29+%2F+%28+800+%2B+x+%29+=+.15+
+80+%2B+.25x+=+.15%2A%28+800+%2B+x+%29+
+80+%2B+.25x+=+120+%2B+.15x+
+.1x+=+40+
+x+=+400+
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400 pounds of hamburger that is 75% lean ( 25% fat )
must be added
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check:
+%28+80+%2B+.25%2A400+%29+%2F+%28+800+%2B+400+%29+=+.15+
+%28+80+%2B+100+%29+%2F+1200+=+.15+
+180+=+.15%2A1200+
+180+=+180+
OK

Answer by stanbon(75887) About Me  (Show Source):
You can put this solution on YOUR website!
The meat department in a grocery store purchased 800 lb of hamburger that is 90% lean beef. How many lbs of hamburger that is 75% lean must be mixed with this 90% lean mix to produce hamburger that is 85% lean beef?
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lean + lean = lean
0.90*800 + 0.75x = 0.85(800+x)
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Multiply thru by 100 to get:
90*800 + 75x = 85*800 + 85x
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10x = 5*800
x = 400 lbs (amt. of 75% lean to add)
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Cheers,
Stan H.
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