Question 770717
how many ounces of pure silver should be added to 180 ounces, 75% pure, to obtain a mixture of 80% pure?
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Equation:
silver + silver = silver
1.00x + 0.75*180 = 0.80(x+180)
100x + 75*180 = 80x + 80*180
20x = 5*180
x = 180/4
x = 45 ounces (amt. of pure silver to add)
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the second question is:
how many pounds of cream containing 30% butterfat should be added to 500 pounds of milk containing 2% butterfat to give milk containing 3.5% butterfat?
Equation:
fat + fat = fat
0.30x + 0.02*500 = 0.035(x+500)
300x + 20*500 = 35x + 35*500
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265x = 15*500
x = 28.3 lbs (amt. of 30% butter fat to add)
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Cheers,
Stan H.