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Of the films Empty Set Studios released last year, 60% were [#permalink]
 10 Aug 2010, 11:44
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Of the films Empty Set Studios released last year, 60% were comedies and the rest were horror films. 75% of the comedies were profitable, but 75% of the horror moves were unprofitable. If the studio made a total of 40 films, and broke even on none of them, how many of their films were profitable? A. 18 B. 19 C. 20 D. 21 E. 22 Above is the first problem on my second online practice test (from Manhattan gmat website). I have worked this problem every way imaginable for hours on end and still can’t figure it. Basically, we’re talking “part / whole” here, right?.... seems simple, so.... 75% (part) / 60%(whole) + 15%(part) / 40%(whole) = x NOTE: I recognize at least that it is 25/40 and not 75/40 because we really want to know how many horror were profitable not unprofitable (100%-75%=25%). So I make this change at the get-to.75/60 + 25/40 = x reduce....and then plug in: 40 - x = ANSWER Someone walk me through this please.... is my 75/60 approach wrong? It must be....should it be 75/100 and 60/100, separately? Then reduce, then multiply or divide the two? I've tried this approach and come up empty handed as well. Someone please show me the light. I'm embarrassed to admit i've stubbornly spent hours racking my brain on this, as I realize this is not a "hard" problem by any means...
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Re: Word Problem w/ Percents, what am I doing wrong? [#permalink]
10 Aug 2010, 12:01
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lifeisshort wrote: Of the films Empty Set Studios released last year, 60% were comedies and the rest were horror films. 75% of the comedies were profitable, but 75% of the horror moves were unprofitable. If the studio made a total of 40 films, and broke even on none of them, how many of their films were profitable?
A 18
B 19
C 20
D 21
E 22
Let me offer another solution: Out of 40 films 60% were comedies and the rest, so 40%, were horror films --> comedies=40*60%=24 and horrors=16; 75% of the comedies were profitable --> profitable comedies=24*75%=18; 75% of the horror moves were unprofitable, so 25% of the horror movies were profitable --> profitable horrors=16*25%=4; Total profitable movies = 18+4=22. Answer: E.
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Re: Word Problem w/ Percents, what am I doing wrong? [#permalink]
10 Aug 2010, 12:04
i got 22. if there are a total of 40 movies and 60% were comedy, then 40% were horror. therefore: 40*.60 = 24 comedy movies 40*.40 = 16 horror movies now we know that 75% of the comedy were profitable. 24*.75 = 18 profitable comedy movies if 75% of the horror were not profitable, then 25% were. 18*.25 = 4 profitable horror 18 + 4 = 22 profitable movies total
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Re: Word Problem w/ Percents, what am I doing wrong? [#permalink]
10 Aug 2010, 12:13
After fiddling some more, this is how I got to answer choice E...but did I get here using voodoo math or is it sound?
(.60*.75) + (.40*.25) = .44 + .10 = .55
55/100 = 11/20
Then subtract from 40:
40 - 11/20 = 22 (answer E)
NOTE:
I see how you both approached this right off by taking both known %'s of 40, getting two solid numbers to work with, and then taking a percentage of both knowns. Smart. Thank you for the keen insight. Your way is definitely the smart way, but is my math above correct or just lucky?
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Re: Word Problem w/ Percents, what am I doing wrong? [#permalink]
10 Aug 2010, 17:47
lifeisshort wrote: After fiddling some more, this is how I got to answer choice E...but did I get here using voodoo math or is it sound?
(.60*.75) + (.40*.25) = .44 + .10 = .55
55/100 = 11/20
Then subtract from 40:
40 - 11/20 = 22 (answer E)
NOTE:
I see how you both approached this right off by taking both known %'s of 40, getting two solid numbers to work with, and then taking a percentage of both knowns. Smart. Thank you for the keen insight. Your way is definitely the smart way, but is my math above correct or just lucky? Quote: Then subtract from 40:
40 - 11/20 = 22 (answer E) Did you mean 40 * (11/20) = 22 ???
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Re: Word Problem w/ Percents, what am I doing wrong? [#permalink]
10 Aug 2010, 19:28
movie_type:horror-----------comedy
% :40---------------60
as we know total movies made = 40
num_movies:16---------------24
profitable :4-----------------18 (3/4 of horror are unprofitable and 3/4 of comedy are profitable)
answer : 18+4 = 22
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Re: Word Problem w/ Percents, what am I doing wrong? [#permalink]
11 Aug 2010, 03:17
Let's imagine, that we have 100 movies.
So we can easily jump from percents to actual figures.
In this case we have 55 profitable movies.
55 profitable movies = 55% of all movies.
But actually only 40 movies were made. So we just find 55% of 40 movies = 22 (E)
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Re: Word Problem w/ Percents, what am I doing wrong? [#permalink]
17 Aug 2010, 12:54
Total profitable movies
comedy - 24*3/4=18
horror - 16*1/4=4
Total - 18+4 =22
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Re: Word Problem w/ Percents, what am I doing wrong? [#permalink]
17 Aug 2010, 15:46
lifeisshort wrote: Of the films Empty Set Studios released last year, 60% were comedies and the rest were horror films. 75% of the comedies were profitable, but 75% of the horror moves were unprofitable. If the studio made a total of 40 films, and broke even on none of them, how many of their films were profitable?
A 18
B 19
C 20
D 21
E 22
*snip*
Someone walk me through this please.... is my 75/60 approach wrong? It must be....should it be 75/100 and 60/100, separately? Then reduce, then multiply or divide the two? I've tried this approach and come up empty handed as well. Someone please show me the light. I'm embarrassed to admit i've stubbornly spent hours racking my brain on this, as I realize this is not a "hard" problem by any means... The only mistake you are doing is in calculating the % (of the profitable movie in this case ) Just keep in mind that mistake, I think it will help in lot of other problems too ! Don't let yourself get confused with part/whole thing. Just remember whole percent and multiply part to while to get actual % of that . I hope this will help you 
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Re: Word Problem w/ Percents, what am I doing wrong? [#permalink]
23 Oct 2011, 05:12
solution
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Re: Word Problem w/ Percents, what am I doing wrong?
[#permalink]
23 Oct 2011, 05:12
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