Milk

[Baldini]

Three grades of milk are 1 percent, 2 percent and 3 percent fat by volume. If x gallons of the 1% grade, y gallons of the 2% grade and z gallons of the 3% grade are mixed up and give a 1.5% grade, what is x in terms of y and z?

a. y + 3z
b. (y+z)/4
c. 2y + 3z
d. 3y + z
e. 3y + 4.5z

OA is A

[bluementor]

Setting up the mixture equation, we get:

0.01x + 0.02y + 0.03z = 0.015(x + y + z)
10x + 20y + 30z = 15(x + y + z) … multiple equation by 1000
10x + 20y + 30z = 15x + 15y + 15z
5y + 15z = 5x
x = y + 3z … divide equation by 5

Choose A.

-BM-

[Vemuri]

The question is basically saying that 0.01x+0.02y+0.03z=0.015(x+y+z)

this can be simplified to x+2y+3z=1.5x+1.5y+1.5z
bringing x on one side, we get ==> 0.5x=0.5y+1.5z
==> x=y+3z

Hope that helps.