gmatblood wrote:A contractor combined x tons of gravel mixture that contained 10 percent gravel G, by weight, with y tons of a mixture that contained 2 percent gravel G, by weight, to produce z tons of a mixture that was 5 percent gravel G, by weight. What is the value of x?
(1) y = 10
(2) z = 16
X = 10%.
Y = 2%.
Z = X+Y = 5%.
According to alligation:
The proportion needed of each ingredient in the mixture is equal to the distance between the OTHER two percentages.
Proportion needed of X = |percentage in Z - percentage in Y| = |5-2| = 3.
Proportion needed of Y = |percentage in Z - percentage in X| = |5-10| = 5.
X : Y = 3:5.
Statement 1: Y=10.
Since 3:5 = 6:10, X=6.
SUFFICIENT.
Statement 2: Z=16.
Thus, X+Y = 16.
Since X:Y = 3:5 = 6:10, X=6 and Y=10.
SUFFICIENT.
The correct answer is
D.
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