gmatquant25 wrote:In a LAB experiment , a 100 ml compound of element X and element Y needs to be increased to 120 ml by adding some quantity of element X, and some quantity of element Y .If the original compound contains 30% of element X , how much (in ml) of element Y must be added so that element X will be exactly one third of the resulting mixture ?
A)40 ml
B)100/3 ml
c)20 ml
D)20/3 ml
E)10 ml
OA E
Amount of X in the original 100ml solution = .3(100) = 30.
Amount of X in the final 120ml solution = (1/3)(120) = 40.
Increase in X = 40-30 = 10.
Total increase in volume between the two solutions = 120-100 = 20.
Since the total increase in volume is 20ml, and the increase in X is only 10ml, the amount of Y added = 20-10 = 10.
The correct answer is
E.
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