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A professional gambler has won 40% of his 25 poker games for [#permalink]
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 03 Jun 2012, 11:37
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A professional gambler has won 40% of his 25 poker games for the week so far. If, all of a sudden, his luck changes and he begins winning 80% of the time, how many more games must he play to end up winning 60% of all his games for the week? A. 20 B. 25 C. 30 D. 35 E. 40
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Re: Percentage problem [#permalink]
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03 Jun 2012, 13:17
Edited with correction.
Last edited by BDSunDevil on 04 Jun 2012, 01:12, edited 1 time in total.
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Re: Percentage problem [#permalink]
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03 Jun 2012, 17:57
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BDSunDevil wrote: He needs to win 60% of all the game, i. e. 60% of 25 = 15
He already won 40% of 25 = 10 games.
He needs to win 5 more.
However his chance is 80%. That is, for every 5 games he play, he win 4.
Therefore, he must play (5*5/4)=6.2= 7 more games to win total 15 games.
What is the OA? The OA is 25 more games.
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Re: Percentage problem [#permalink]
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03 Jun 2012, 23:54
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Sorry for the last post.
If he plays X more games, the equation becomes:
games with 40% chance + Games with 80% chance = Total games with 60% chance
.40*25 + .80*X=.60*(25+X)
Solving for X = 25
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Re: A professional gambler has won 40% of his 25 poker games for [#permalink]
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04 Jun 2012, 00:41
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Re: A professional gambler has won 40% of his 25 poker games for [#permalink]
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04 Jun 2012, 02:52
farukqmul wrote: A professional gambler has won 40% of his 25 poker games for the week so far. If, all of a sudden, his luck changes and he began winning 80% of the time, how many more games must he play to end up winning 60% of all his games for the week? explanation is given in MGMAT book but I didn't understand it...Can anyone please explain? Responding to a pm: Yes, you can use the weighted averages method. w1/w2 = (80 - 60)/(60 - 40) = 1:1 'The number of games out of which he won 40% games' is equal to 'the number of games out of which he must win 80% of the games'. He won 40% of the games out of 25 games. So he must win 80% of the games out of another 25 games.
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Re: A professional gambler has won 40% of his 25 poker games for [#permalink]
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04 Jun 2012, 05:21
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Hi, Initially the person has played 25 games with probablity of winning as 40% Thus, number of games won = 10 Later when the probability of winning changes to 80% and assuming x games were played by him: Total number of win, 60% of all games \(= 0.6(x+25) = 10 + 0.8x\) \(0.2x=5\) \(x=25\) so, he has to play 25 games. Alternatively, this could be solved by allegation method. B = 25games. Regards,
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Re: Percentage problem [#permalink]
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04 Jun 2012, 07:31
davidandcompany wrote: farukqmul wrote: A professional gambler has won 40% of his 25 poker games for the week so far.If,all of a sudden,his luck changes and he began winning 80% of the time,how many more games must he play to end up winning 60% of all his games for the week? explanation is given in MGMAT book but I didn't understand it...Can anyone please explain? Let x = number of games more must he play 0.4(25) + 0.8x = 0.6(25+x) <--- You should be able to grasp this idea. 10 + 0.8x = 15 + 0.6x 0.8x - 0.6x = 15 - 10 0.2x = 5 x = 25 Hi, can you explain the equation please ?
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Re: Percentage problem [#permalink]
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04 Jun 2012, 07:33
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Re: A professional gambler has won 40% of his 25 poker games for [#permalink]
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26 Aug 2013, 06:59
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Re: A professional gambler has won 40% of his 25 poker games for [#permalink]
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27 Aug 2013, 18:58
Using alligation method
40 80
60
20 20 ==> 1:1
Must play another 25 games
Ans:B
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Re: A professional gambler has won 40% of his 25 poker games for [#permalink]
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Re: A professional gambler has won 40% of his 25 poker games for [#permalink]
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17 Apr 2016, 08:56
ok, the question says that 40% of the games 25 games are won => 10 games.
then the question says that 60% of all the games are won => 60% ( x + 25)
it tells you that 80% of the remaining games are won => 80% (x)
the equation is => 40%(25) + 80%(x) = 60% (x+25) => 10+ .80x = .6x + 15 => .2x = 10 => x = 25.
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Re: A professional gambler has won 40% of his 25 poker games for [#permalink]
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07 Jun 2017, 20:53
Bunuel wrote: farukqmul wrote: A professional gambler has won 40% of his 25 poker games for the week so far. If, all of a sudden, his luck changes and he began winning 80% of the time, how many more games must he play to end up winning 60% of all his games for the week? explanation is given in MGMAT book but I didn't understand it...Can anyone please explain? This is a simple weighted average question. Say the gambler must play x more games, then: 40% of 25 games plus 80% of x games should equal to 60% of total number of games, which is (25+x) --> 0.4*25+0.8*x=0.6*(25+x) --> x=25. Hope it's clear. - this is the same formula I derived- do we need to necessarily plug in and test each of the answer choices? Or can we just simplify the equation?
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Re: A professional gambler has won 40% of his 25 poker games for [#permalink]
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10 Jun 2017, 08:31
farukqmul wrote: A professional gambler has won 40% of his 25 poker games for the week so far. If, all of a sudden, his luck changes and he begins winning 80% of the time, how many more games must he play to end up winning 60% of all his games for the week?
A. 20
B. 25
C. 30
D. 35
E. 40 We are given that a poker player has won 0.4 x 25 = 10 poker games. If he starts winning 80% of his games, we need to determine how many more games must be played to have a winning percentage of 60% for the week. We can let x = the number of additional games played and we have: (10 + 0.8x)/(25 + x) = 60/100 (10 + 0.8x)/(25 + x) = 3/5 5(10 + 0.8x) = 3(25 + x) 50 + 4x = 75 + 3x x = 25 Answer: B
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Re: A professional gambler has won 40% of his 25 poker games for [#permalink]
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10 Jun 2017, 08:34
farukqmul wrote: A professional gambler has won 40% of his 25 poker games for the week so far. If, all of a sudden, his luck changes and he begins winning 80% of the time, how many more games must he play to end up winning 60% of all his games for the week?
A. 20
B. 25
C. 30
D. 35
E. 40 We are given that a poker player has won 0.4 x 25 = 10 poker games. If he starts winning 80% of his games, we need to determine how many more games must be played to have a winning percentage of 60% for the week. We can let x = the number of additional games played and we have: (10 + 0.8x)/(25 + x) = 60/100 (10 + 0.8x)/(25 + x) = 3/5 5(10 + 0.8x) = 3(25 + x) 50 + 4x = 75 + 3x x = 25 Answer: B
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Re: A professional gambler has won 40% of his 25 poker games for
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10 Jun 2017, 08:34
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