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GMAT Prep?? (Sight-Seeing Tour)

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GMAT Prep?? (Sight-Seeing Tour)

by dferm » Mon May 05, 2008 7:22 am
On a certain sight-seeing tour, the ratio of the number of women to the number of children was 5 to 2. What was the number of men on the sight-seeing tour?

(1) On the sight-seeing tour, the ratio of the number of children to the number of men was 5 to 11

(2) The number of women on the sight-seeing tour was less than 30.

Please Explain....

I got this question Correct..but seem to have a little difficulty setting up the equation..Can someone help?

Thanks.
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by zacharyz » Mon May 05, 2008 9:13 am
Given
Women to Children
5 : 2

You are given a ratio, but not real numbers of people. So at this point, the number of women could be any multiple of 5.

Answer A - insufficient
You now have the ratio of children to men, but no "real numbers"
Children to Men
5 : 11

For reference, you now have a translation from women to men also. You need to have the translation (aka CHILDREN) to have the name number though. So, let's multiply the first equation by 5 and the second equation by 2:
Women to Children Children to Men
25 : 10 10 : 22
therefore:
Women to Children to Men:
25 : 10 : 22

Answer B - insufficient
This gives you nothing about the number of men AND it doesn't really tell you the number of women.


Put them together:
From statement (A), you have a translation from a hypothetical number of women (namely 25) to a hypothetical number of men (22). You cannot reduce the ratio 25:10:22 any further as they share no factors other than 1. Therefore, if there were less than 30 women, there had to have been exactly 25. And now you know there were 22 men.

So the answer is (C) - Both together are required.


For arguments sake, if (B) had given "the number of women was less than 60," then you still don't know the number of men. Because you could have had 25 women and 22 men or 50 women and 44 men.
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by ksh » Mon May 05, 2008 11:49 pm
1. Insufficient w/c=5/2 =>c=2w/5

2. Insufficient c/m=5/11, m=11*2w/25

since no. of women on the tour are less than 30, it can not definitely be determined how many men are there.

IMO E
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Is it the right ans?
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by Stuart@KaplanGMAT » Tue May 06, 2008 8:32 am
ksh wrote:1. Insufficient w/c=5/2 =>c=2w/5

2. Insufficient c/m=5/11, m=11*2w/25

since no. of women on the tour are less than 30, it can not definitely be determined how many men are there.

IMO E
------------------
Is it the right ans?
C is correct.

You have to remember that in certain cases, we can deduce that the variables stand for integers.

It's impossible to have 12.5 women. So, even though algebraically there could be other values for w, since w stands for an indivisible object we know that w=25, at which point we can solve for everything else too.
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by amitansu » Wed May 07, 2008 12:37 am
I think this is a classic example of GMAT trap !!

In the q it asks for a perticular no. not a ratio !! so 1) is insufficient
from 2 we can say we have W < 30

And as it is, we can't have a GCD of both 25 and 22 (W/M=25/22)
we have to stick that fact tha W=25 and M=22 !!

Thanks Stuart again for this wonderful solution !!

Amit
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Concepts

by vladmire » Wed Dec 03, 2008 7:51 pm
Why do we multiply both ratios by 2 was that just a random number?
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by wrtau23 » Wed Jan 07, 2009 2:36 pm
I think it is to get the number of children to match in both ratios so we could have the rations of men to women, is this correct?
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by vscid » Wed Jan 07, 2009 7:47 pm
C it is. Typical GMAT trap :D
The GMAT is indeed adaptable. Whenever I answer RC, it proficiently 'adapts' itself to mark my 'right' answer 'wrong'.
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by vivek.kapoor83 » Thu Jan 08, 2009 12:24 am
let M, W, C represent number of men, women and children on tour

given w/c = 5/2 or C = 2W/5

from I: C/M = 5/11 or C = 5M/11

equqting C from two equations: 2W/5 = 5M/11 or M = 22W/25

no further info.................not sufficient

from II: W < 30

not sufficient alone

BOTH I and II: as W < 30
and M = 22W/25, only one value of W=25 will satisfy as people caanot be in fractions

M = 22

both together, not alone Ans:C
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by coffee5251 » Thu Jan 08, 2009 10:18 am
zacharyz wrote:
Put them together:
From statement (A), you have a translation from a hypothetical number of women (namely 25) to a hypothetical number of men (22). You cannot reduce the ratio 25:10:22 any further as they share no factors other than 1. Therefore, if there were less than 30 women, there had to have been exactly 25. And now you know there were 22 men.

So the answer is (C) - Both together are required.
If you had picked a number other than 5 to multiply the ratios by, the answer wouldn't have just fallen into place in the 25:10:22 ratio like the example above. How would you go about this in 2 minutes if the first multiplier chosen had been for example 3 or 4 or 9? Is there a way to know you should choose 5 so you don't waste time guessing and checking?
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ratio problem

by bido » Tue Feb 03, 2009 3:28 pm
GIVEN; W/C =5/2

1) C/M=5/11 therefore W/C *C/M = W/M =25/22..therefore 1 is not sufficient since M could be 22,44,66,88 i.e multiply of 22

2) W is less than 30...statement 2 is not sufficient cuz doesnt mention abt men

Together...since W/M=25/22 and W is less than 30....therefore W can only be 25 given the ratio and M can only be 22 given the ratio.

thnks ..hope its clear. C is the ANSWER
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by abcdefg » Sun Jul 19, 2009 6:34 am
just out of curiosity, what cues told you guys to look beyond the "GMAT Trap"? When I first did this, I choose E.
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by Musicolo » Sun Jul 19, 2009 12:22 pm
I still don't get it guys. Can someone please explain how C is correct? Pleeeeeeease?
Thanks.
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by deepakteja1988 » Thu Jul 07, 2011 11:53 am
women = w
men = m
children = c

given : w/c = 5/2 , to find m = ?

a. c/m = 5/11 => 11c = 5m , 5c = 2w (given) => 2w/5 = 5m/11 => m= 22w/25. For m to be a integer (number of men), w has to be multiple of 25. Like 25, 50, 75 and so....
So a alone is insufficient.

b. w is less than 30.

So from A and B , w = 25 => m = 22

The best way I felt we can solve this problem :)
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by rishijhawar » Sun Jul 10, 2011 3:59 am
Another option without equations:
Original ratios:
___W_______C_________

____5______2

Combined result from A:
___W_______C_________M____

____5______2______________

____________5_________11____

___25______10_______22

But the actual numbers can be 50,20,44/100,40,88...... INSUFFICIENT

From B, we know the number of women<30. No info about Men. INSUFFICIENT

From A & B: number of women = 25 hence number of men=22.
So, C
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