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winning 50 percent

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anoo.anand
 Post subject: winning 50 percent
 Post Posted: Sun Sep 20, 2009 4:41 pm 
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Students


Posts: 74
After winning 50 percent of th first 20 games it played. Team A won all of the remaining games it played. What was the total number of games that team A won ?

1) Team A played 25 games altogether.
2) Team A won 60% of all the games it played.


The problem I am facing is option 2 does not give us the exact answer then how can we say that Option B is also correct.

It gives the answer in some variable form but not the exact value as in A , please help to explain, why is option B correct also. ?
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gupta.ab
 Post subject: Re: winning 50 percent
 Post Posted: Mon Sep 21, 2009 1:53 am 
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Posts: 5
Need to Find: Total no of games A won
Question provides us information :

of 20 games won 10
of rest (say X) won X
So,

Played : 20+x
Won: 10+x

Hence we need to find X

1) 20+x = 25
we can solve for X : SUFF

2) 60/100 (20+x) (games played) = 10+x (games won)
We can solve for X : SUFF

Answer: D
In both cases we get x=5
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bscully27
 Post subject: Re: winning 50 percent
 Post Posted: Mon Jul 05, 2010 12:16 am 
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Course Students


Posts: 1
My problem with this question is that there is no upper bound on statement 2 which says, "Team A won 60% of all the games it played."

So Team A could have played 25 (5 additional) as shown in the earlier posts OR they could have played 100 games (80 additional) and won 60%. So essentially there is a limitless amount of total games that Team A could have played, thus making statement 2 insufficient.

If the question stated, "what is the minimum number of games" or something to that extent, I would agree with the answer. Given that is not the case, this is a BAD (unclear) GMAT question....

Anyone else agree?
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RonPurewal
 Post subject: Re: winning 50 percent
 Post Posted: Sun Aug 01, 2010 3:28 am 
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ManhattanGMAT Staff


Posts: 6765
bscully27 wrote:
My problem with this question is that there is no upper bound on statement 2 which says, "Team A won 60% of all the games it played."

So Team A could have played 25 (5 additional) as shown in the earlier posts OR they could have played 100 games (80 additional) and won 60%. So essentially there is a limitless amount of total games that Team A could have played, thus making statement 2 insufficient.

If the question stated, "what is the minimum number of games" or something to that extent, I would agree with the answer. Given that is not the case, this is a BAD (unclear) GMAT question....

Anyone else agree?


nope -- i think you're neglecting the other condition in the problem, namely, that the team must win all of the additional games. so that's going to yield exactly one # of games after which the total winning percentage is 60%.

you can actually figure this out without doing any math at all. here's how:
the winning percentage starts at 50%, after the first 20 games.
from this point onward, the team wins every game, thus making the winning percentage go up with each new game (this is what happens when you win: the winning % goes up, unless it's already 100%). therefore, since the winning percentage just goes up and up and up, there will be exactly one time when it will be 60%. therefore, the statement is sufficient.
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RonPurewal
 Post subject: Re: winning 50 percent
 Post Posted: Sun Aug 01, 2010 3:30 am 
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ManhattanGMAT Staff


Posts: 6765
RonPurewal wrote:
bscully27 wrote:
My problem with this question is that there is no upper bound on statement 2 which says, "Team A won 60% of all the games it played."

So Team A could have played 25 (5 additional) as shown in the earlier posts OR they could have played 100 games (80 additional) and won 60%. So essentially there is a limitless amount of total games that Team A could have played, thus making statement 2 insufficient.

If the question stated, "what is the minimum number of games" or something to that extent, I would agree with the answer. Given that is not the case, this is a BAD (unclear) GMAT question....

Anyone else agree?


nope -- i think you're neglecting the other condition in the problem, namely, that the team must win all of the additional games. so that's going to yield exactly one # of games after which the total winning percentage is 60%.

you can actually figure this out without doing any math at all. here's how:
the winning percentage starts at 50%, after the first 20 games.
from this point onward, the team wins every game, thus making the winning percentage go up with each new game (this is what happens when you win: the winning % goes up, unless it's already 100%). therefore, since the winning percentage just goes up and up and up, there will be exactly one time when it will be 60%. therefore, the statement is sufficient.


if you want a more traditional algebraic solution, check out the post up there with the (10+x) and (20+x); that solution is beautifully done.
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