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Need help with this one.
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akshaydhande
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DavidG@VeritasPrep
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Notice that 1.5% is the midpoint between 1% and 2%. So if you had only 1% milk (x) and 2% milk (y), and the combined solution was 1.5% fat, you'd have equal amounts of x and y. If z = 0, we won't have any 3% milk to worry about. Put another way, if z = 0, then x = y. So we can plug in 0 for z in the answer choices, and see what gives us y by itself.Three grades of milk: 1%, 2%, and 3% fat by volume. x gallons of 1%, y gallons of 2%, and z gallons of 3% are mixed to give x + y + z gallons of 1.5%. What is x in terms of y and z?
a) y + 3z
b) (y + z)/4
c) 2y + 3z
d) 3y + z
e) 3y + 4z
In answer choice A, if z = 0, then we have y + 3*0 = y. That's our answer.
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Brent@GMATPrepNow
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Let's start with a "word equation" and slowly turn it into an algebraic expression:Three grades of milk: 1%, 2%, and 3% fat by volume. X gallons of 1%, y gallons of 2%, and z gallons of 3% are mixed to give x + y + z gallons of 1.5%. What is x in terms of y and z?
a. y + 3z
b. (y + z)/4
c. 2y + 3z
d. 3y + z
e. 3y + 4z
Total fat in mixture = 1.5% of (x+y+z)
(1% of x) + (2% of y) + (3% of z) = 0.015(x+y+z)
Rewrite as: 0.01x + 0.02y + 0.03z = 0.015x + 0.015y + 0.015z
Multiply both sides by 100: 1x + 2y + 3z = 1.5x + 1.5y + 1.5z
Rearrange and simplify: 0.5y + 1.5z = 0.5x
Multiply both sides by 2 to get: y + 3z = x
Answer = A
Cheers,
Brent
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Hi akshaydhande,
This is an "in terms of" question; these questions are usually built around 4-5 algebra steps and are fairly straight-forward "math" questions.
First, translate the equation:
[(.01x) + (.02y) + (.03z)] / {x + y + z] = .015
.01x + .02y + .03z = .015x + .015y + .015z
Let's multiply everything by 1000 to get rid of the decimals....
10x + 20y + 30z = 15x + 15y + 15z
5y + 15z = 5x
y + 3z = x
Final Answer: A
GMAT assassins aren't born, they're made,
Rich
This is an "in terms of" question; these questions are usually built around 4-5 algebra steps and are fairly straight-forward "math" questions.
First, translate the equation:
[(.01x) + (.02y) + (.03z)] / {x + y + z] = .015
.01x + .02y + .03z = .015x + .015y + .015z
Let's multiply everything by 1000 to get rid of the decimals....
10x + 20y + 30z = 15x + 15y + 15z
5y + 15z = 5x
y + 3z = x
Final Answer: A
GMAT assassins aren't born, they're made,
Rich
