Can you help me find the correct answer para po sa mixture problem? ito po ang problem: "drew, a chemistry student, wanted to take experiments with an available solution of 70% and 40% alcohol. he was instructed to prepare a 150 ml solution with 60% alcohol mixing from each other. how much solution should he use?" i got the value of y as 15 and x as135. is this the correct answer?? help me please!! thanks a lot..:)


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Answers

2014-10-10T18:02:58+08:00
Let 'x'  be the amount with 70% alcohol
    'y' be the amount with 40% alcohol
you're given that the resulting solution must be 60% concentrated and that the total amount would be 150ml. from there we can say that
x + y = 150  ------let this be equation 1
in getting the desired concentration, you'll have the equation as:
0.70x + 0.40y = 0.60(150)  -----equation 2
from equation 1, we can get the value of x in terms of y
x + y = 150
x = 150 - y -----equation 3
substitute equation 3 to 2
0.70x + 0.40y = 0.60(150)
0.70(150 - y) + 0.40y = 90
105 - 0.70y + 0.40y = 90
-0.70y + 0.40y = 90 - 105
-0.30y = -15
y = 50ml
substituting the value of y in equation 3
x = 150 - y
x = 150 - 50
x = 100ml
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