Official Guide Explanation:
Data Sufficiency #94




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Solution and Metadata

Question: 94
Page: 160
Difficulty: 5 (Moderate)
Category 1: Algebra > Equations >
Category 2: Arithmetic > Fractions >

Explanation: Statement (1) is insufficient. Because the equations given could cause variables to cancel out, it's important to check and make sure that they don't give you enough information. First, substitute in x = ((y)/2)

((x)/(yz)) = ((((y)/2))/(yz)) = ((y)/2)((1/(yz))) = ((y)/(2yz)) = (1/(2z))

If you then substitute z = ((2x)/5) into that fraction, you'll be left with a variable, so you can't find a numerical value of ((x)/(yz)).

Statement (2) is sufficient:

((x)/(yz)) = ((1/(y)))(((x)/(z))) = ( (1/10))((5/2)) = (5/20) = (1/4)

(B) is the correct choice.

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