Nifty trick for this difficult question:
Add +1 to both sides of the inequality in (1). You get:
r/(b+w) +1 > w/(b+r) +1
combine the 1 with the fractions on either side:
r+(b+w) / b+w > w+(b+r) / (b+r)
Note that the numerators are now the same r+b+w (the total number of options). Cross multiply to put that quantity in the bottom and make for a proper probability function:
(b+r)/ w+b+r > b+w / w+b+r
It follows that r>w, and the answer is yes.
Stat. (2) is insufficient with plugging in - you can find two opposing scenarios, where r is both smaller and greater than w, depending on the value of b.
GMAT Prep : Probability
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Source: Beat The GMAT — Data Sufficiency |
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Geva@EconomistGMAT
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Geva
Thanks a lot. With exams just a week away...anything that I 'm not able to solve gets me all worked up. After looking at your solution, the sum seems so simple....
Hope these things strike a chord when the D day comes.
cheers
Thanks a lot. With exams just a week away...anything that I 'm not able to solve gets me all worked up. After looking at your solution, the sum seems so simple....
Hope these things strike a chord when the D day comes.
cheers
StAy HuNgry sTay fOOlisH
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Geva@EconomistGMAT
- GMAT Instructor
- Posts: 905
- Joined: Sun Sep 12, 2010 1:38 am
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- GMAT Score:760
You're more than welcome.Skywalker wrote:Geva
Thanks a lot. With exams just a week away...anything that I 'm not able to solve gets me all worked up. After looking at your solution, the sum seems so simple....
Hope these things strike a chord when the D day comes.
cheers
Good luck on your test.
