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A total of 30 percent of the geese included in a certain
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Updated on: 07 Oct 2013, 01:29
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A total of 30 percent of the geese included in a certain migration study were male. If some of the geese migrated during the study and 20 percent of the migrating geese were male, what was the ratio of the migration rate for the male geese to the migration rate for the female geese? [Migration rate for geese of a certain sex = (number of geese of that sex migrating) / (total number of geese of that sex)]
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27 Mar 2017, 17:28
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ajit257 wrote:
A total of 30 percent of the geese included in a certain migration study were male. If some of the geese migrated during the study and 20 percent of the migrating geese were male, what was the ratio of the migration rate for the male geese to the migration rate for the female geese? [Migration rate for geese of a certain sex = (number of geese of that sex migrating) / (total number of geese of that sex)]
A. 1/4 B. 7/12 C. 2/3 D. 7/8 E. 8/7
We can let t = the total number of geese before migration; thus, the number of male geese = 0.3t and the number of female geese = 0.7t. If we let the number of migrating geese = m, then the number of male migrating geese = 0.2m and the number of female migrating geese = 0.8m.
Thus, the migration rate for the male geese is 0.2m/0.3t = 2m/3t and the migration rate for the female geese is 0.8m/0.7t = 8m/7t.
Thus, the ratio of male migration rate to female migration rate is:
(2m/3t)/(8m/7t) = (7t x 2m)/(3t x 8m) = (14mt)/(24mt) = 14/24 = 7/12.
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06 Jan 2011, 00:24
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ajit257 wrote:
A total of 30 percent of the geese included in a certain migration study were male. If some of the geese migrated during the study and 20 percent of the migrating geese were male, what was the ratio of the migration rate for the male geese to the migration rate for the female geese? [Migration rate for geese of a certain sex = (number of geese of that sex migrating) / (total number of geese of that sex)]
A. 1/4 B. 7/12 C. 2/3 D. 7/8 E. 8/7
Let there be g geese, of which 0.3g are male and 0.7g are female Lets say m geese migrated, 0.2m are male and 0.8m are female
Re: A total of 30 percent of the geese
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05 Jan 2011, 23:05
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Let there be 100 geese. Out of these since there were 30% male then there were 70 females, let the number of migrating birds be X, out of the ones migrating 20% were males so .8x where females. so, 7/8 (D)
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23 Mar 2017, 19:45
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Taking 100 as the number of geese in the study, 30 are male and 70 are female. Setting the number of geese that migrate as 5x, the number of male geese migrating is x (20%), and the number of female geese migrating is 4x (80%).
Re: A total of 30 percent of the geese included in a certain
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08 Feb 2018, 20:08
hjli89 wrote:
MartyMurray wrote:
Let' take the Number of geese to be 100.
You could use the same method, but with simpler numbers.
30 males
70 females
Any 20/80 ratio for males migrating to females migrating will work. So, you could use the following.
10 males migrated
40 females migrated
male migration ratio: 10/30 = 1/3
female migration ratio: 40/70 = 4/7
(1/3)/(4/7) = 7/12
Choose B, and you are on to the next question.
Enjoy the GAME!
Great explanation! Can someone quickly point out why you divide (1/3) by (4/7) in order to take the ratio of those?
Thanks
[/quote] [Migration rate for geese of a certain sex = (number of geese of that sex migrating) / (total number of geese of that sex)] the migration rate for the male geese = 1/3 the migration rate for the female geese=4/7 BUT we have to find RATIO of these rates:- "theratio of the migration rate for the male geese to the migration rate for the female geese?"
Re: A total of 30 percent of the geese included in a certain
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09 Oct 2018, 23:12
Let's say 30 male and 70 female studied. Let' say, of 100 geese, 60 were migrating. 12 males migrating, 48 female migrating. Male rate: 12/30=2/5 Female rate: 48/70=24/35 Male/Female=5*24/2*35= 7/12
Concentration: International Business, General Management
GMAT 1: 680 Q44 V39
Re: A total of 30 percent of the geese included in a certain
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05 May 2019, 03:55
ajit257 wrote:
A total of 30 percent of the geese included in a certain migration study were male. If some of the geese migrated during the study and 20 percent of the migrating geese were male, what was the ratio of the migration rate for the male geese to the migration rate for the female geese? [Migration rate for geese of a certain sex = (number of geese of that sex migrating) / (total number of geese of that sex)]
A. 1/4 B. 7/12 C. 2/3 D. 7/8 E. 8/7
This can be solved easily using a Double Matrix Method. Refer the attached pic.
Re: A total of 30 percent of the geese included in a certain
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09 Jul 2019, 06:42
Im surprised to see that this question is 700 level. I'm saying this not because I found it easy (I actually got it wrong) but more of it can be solved by just deeper comprehension and no sophisticated formula or deep math number theory necessary. I noticed that this is one of my weaknesses, the PERCENT within another PERCENT type of questions.
Re: A total of 30 percent of the geese included in a certain
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09 Jul 2019, 06:55
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Diwabag wrote:
Im surprised to see that this question is 700 level. I'm saying this not because I found it easy (I actually got it wrong) but more of it can be solved by just deeper comprehension and no sophisticated formula or deep math number theory necessary. I noticed that this is one of my weaknesses, the PERCENT within another PERCENT type of questions.
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70% (02:30) correct 
