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A dietitian wishes to plan a meal around three foods: The percentages of the daily requirements carbohydrates,
and iron contained in each ounce of the protein. three foods are summarized in the following table:
Food I Food II Food III
Protein (%) 10 6 8
Carbohydrate (%) 10 12 6
Iron (%) 5 4 12
Determine how many ounces of each food the dietitian should include in the meal
to meet exactly the daily requirements of protein; carbohydrates, and iron ( 100% of each).
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x ounces of Food I; y ounces of Food II and z ounces of Food III.
Write equations as you read the problem
0.10x + 0.06y + 0.08z = 1 (1) (protein)
0.10x + 0.12y + 0.06z = 1 (2) (carbohydrates)
0.05x + 0.04y + 0.12z = 1 (3) (iron)
Now you have different options: you can solve the system of equation manually,
or use some online solver from the Internet, or use the matrix method of your pocket calculator.
The ANSWER is x = 4, y = 2, z = 6 : 4 ounces of Food I, 2 ounces of Food II, 6 ounces of Food III.
I used online solver www.reshish.com, which is free of charge.
Also, there is similar solver at this site, www.algebra.com. Its link is
https://www.algebra.com/algebra/homework/Matrices-and-determiminant/cramers-rule-3x3.solver
Solved.