Please note that this is not an official GMAT question; it’s my attempt to create mid-range (500 to 650-level) GMAT-style questions for this forum.
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Equivalent fractions/ratios
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Brent@GMATPrepNow
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Please note that this is not an official GMAT question; it’s my attempt to create mid-range (500 to 650-level) GMAT-style questions for this forum.
Brent Hanneson - Creator of GMATPrepNow.com
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cramya
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A
Is w/x = y/z
Is wz-xy/xz = 0
We know xz <> 0 therefore the question boils down to Is wz-xy=0 (I.E WZ=XY)
Stmt I
w/y = x/z
wz-xy/yz = 0
yz<>0 therefore wz-xy = 0
SUFF
Stmt II
wy=xz
x=y=w=z=1 YES
x=2 y=2 w=1 z=1 NO
INSUFF
Hope I din't fall for a trap.
Regards,
CR
Is w/x = y/z
Is wz-xy/xz = 0
We know xz <> 0 therefore the question boils down to Is wz-xy=0 (I.E WZ=XY)
Stmt I
w/y = x/z
wz-xy/yz = 0
yz<>0 therefore wz-xy = 0
SUFF
Stmt II
wy=xz
x=y=w=z=1 YES
x=2 y=2 w=1 z=1 NO
INSUFF
Hope I din't fall for a trap.
Regards,
CR
GMAT/MBA Expert
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Brent@GMATPrepNow
- GMAT Instructor
- Posts: 16207
- Joined: Mon Dec 08, 2008 6:26 pm
- Location: Vancouver, BC
- Thanked: 5254 times
- Followed by:1268 members
- GMAT Score:770
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lunarpower
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not bad. and very gmat-like, too. well done.
only one comment:
WHENEVER you talk about "cross multiplication", you should always note that this only works for equations.
after all, there isn't really a such thing as "cross multiply"; cross-multiplication is really just multiplication by both denominators.
if you're using an INEQUALITY, then this can get you into big, big trouble. unless you know the sign of the product of the denominators (which is equivalent to knowing whether the denominators have the same sign), you can't "cross multiply" because you won't know what will happen to the inequality sign.
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in sum:
if you get a PROPORTION (i.e., fraction EQUALS fraction), you can and should cross-multiply.
if you get an INEQUALITY with two fractions, unfortunately, you have to leave it in fractional form unless you know the relative signs of the denominators.
only one comment:
WHENEVER you talk about "cross multiplication", you should always note that this only works for equations.
after all, there isn't really a such thing as "cross multiply"; cross-multiplication is really just multiplication by both denominators.
if you're using an INEQUALITY, then this can get you into big, big trouble. unless you know the sign of the product of the denominators (which is equivalent to knowing whether the denominators have the same sign), you can't "cross multiply" because you won't know what will happen to the inequality sign.
--
in sum:
if you get a PROPORTION (i.e., fraction EQUALS fraction), you can and should cross-multiply.
if you get an INEQUALITY with two fractions, unfortunately, you have to leave it in fractional form unless you know the relative signs of the denominators.
Ron has been teaching various standardized tests for 20 years.
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Pueden hacerle preguntas a Ron en castellano
Potete chiedere domande a Ron in italiano
On peut poser des questions à Ron en français
Voit esittää kysymyksiä Ron:lle myös suomeksi
--
Quand on se sent bien dans un vêtement, tout peut arriver. Un bon vêtement, c'est un passeport pour le bonheur.
Yves Saint-Laurent
--
Learn more about ron
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Pueden hacerle preguntas a Ron en castellano
Potete chiedere domande a Ron in italiano
On peut poser des questions à Ron en français
Voit esittää kysymyksiä Ron:lle myös suomeksi
--
Quand on se sent bien dans un vêtement, tout peut arriver. Un bon vêtement, c'est un passeport pour le bonheur.
Yves Saint-Laurent
--
Learn more about ron
