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GMAT Prep DS - Ratios Question

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GMAT Prep DS - Ratios Question

by ri2007 » Tue Sep 04, 2007 11:28 am
In a tour, the ratio of number of women to the number of children is 5 to 2. What was the number of men on the tour?

1) The ratio of the number of children to men is 5 to 11
2) The number of women was less than 30

Ans is C.

Can any one help me understand this? I keep getting 2 possibilities to satisfy all the above conditions i.e

Number of Women, Children and Men could be 10, 5 & 11 or 20, 10 & 22. So number of men could be 11 or 22.

Where am I going wrong?

Thanks a lot in advance
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by samirpandeyit62 » Tue Sep 04, 2007 9:24 pm
The Logic here is fairly simple

Question says ratio of women to childern lets say W/C = 5/2

stmt1 says ratio of nos of children to men let says C/M = 5/11

Now these ratios have C common between them hence to look at them together we need to make C equal in both ratios
We can do this by multiplying w/c with 5 & c/m with 2 to make C =10 in both ratio's i.e
w/c = 25/10 & c/m =10/22

combining both we can sat w:c:m =25:10:22

but this can't answer the question as we cannot ascertain the nos of men till he we have actual value of either w or c. hence NOT SUFF

stmt 2: says that nos of women is less than 30 from which we cannot draw any inference about nos of men with data w/c =5/2 hence NOT SUFF

Now if combine both then we know that

w:c:m =25:10:22 & nos of women is < 30

now only value less that 30 which will staisfy the above ratio is 25 hence 25 is actual nos of women so nos of men =22 SUFFICEINT

Hence the ans is "C"
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by ri2007 » Wed Sep 05, 2007 5:26 am
Thanks a lot to both you and ashishjain_cu. It was rather silly of my, I got the ratio 20:10:22 and then reduced by 2 forgetting like I would if I was just comparing a ratio between two numbers. Just goes to show how many stupid mistakes one can make
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