SOLUTION: A nurse needs 50 mL of a 16% salt solution for a patient. She can only find a 13% salt solution and an 18% salt solution in the supply room. How many millimeters of the 13% solutio

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Question 1129899: A nurse needs 50 mL of a 16% salt solution for a patient. She can only find a 13% salt solution and an 18% salt solution in the supply room. How many millimeters of the 13% solution should be mixed with the 18% solution to produce the desired amount of the 16% solution?
Found 2 solutions by josmiceli, stanbon:
Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
Let +a+ = mL of 13% solution needed
Let +b+ = mL of 18% solution needed
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(1) +a+%2B+b+=+50+
(2) +%28+.13a+%2B+.18b+%29+%2F+50+=+.16+
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(2) +.13a+%2B+.18b+=+8+
(2) +13a+%2B+18b+=+800+
Multiply both sides of (1) by +13+ and
subtract (1) from (2)
(1) +-13a+-+13b+=+-650+
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+5b+=+150+
+b+=+30+
and
(1) +a+%2B+30+=+50+
(1) +a+=+20+
You can finish

Answer by stanbon(75887) About Me  (Show Source):
You can put this solution on YOUR website!
A nurse needs 50 mL of a 16% salt solution for a patient. She can only find a 13% salt solution and an 18% salt solution in the supply room. How many millimeters of the 13% solution should be mixed with the 18% solution to produce the desired amount of the 16% solution?
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Equation::
salt + salt = salt
0.13x + 0.18(50-x) = 0.16*50
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13x + 18(50) - 18x = 16*50
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5x = 2*50
x = 20mL (amt. of 13% solution needed)
50-x = 30mL (amt. of 18% solution needed)
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Cheers,
Stan H.
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