SOLUTION: Science and medicine. A pharmacist wishes to prepare 150 mL of a 20% alcohol
solution. She has a 30% solution and a 15% solution in her stock. How much of each should be used in f
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solution. She has a 30% solution and a 15% solution in her stock. How much of each should be used in f
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Question 74968: Science and medicine. A pharmacist wishes to prepare 150 mL of a 20% alcohol
solution. She has a 30% solution and a 15% solution in her stock. How much of each should be used in forming the desired mixture?
You can put this solution on YOUR website! Let us suppose that 'x' ml of 30% alcohol be mixed with 'y' ml of 15% alcohol to form 150 ml of 20% alcohol.
150 ml of 20% alcohol consists = 30 ml of alcohol and (150 - 30) = 120 ml of water.
Similarly, 'x' ml of 30% alcohol contains = 0.3x ml and (x - 0.3x) = 0.7x ml of water.
Also, 'y' ml of 30% alcohol contains = 0.15y ml and (y - 0.15y) = 0.85y ml of water.
Thus total volume of alcohol in final mixture = (0.3x + 0.15y) ml and total volume of water in final mixture = (0.7x + 0.85y) ml.
But final mixture contains 30 ml alcohol and 120 ml water.
So, ______________(1)
and ______________(2)
Multiplying (1) by 7 and (2) by 3 and subtracting (1) from (2)
So, [from (1)]
Hence, 50 ml of 30% alcohol should be mixed with 100 ml of 15% alcohol.
