GMAT Prep?? (Sight-Seeing Tour)

dferm · Posted: Mon May 05, 2008 8:22 am Post subject: GMAT Prep?? (Sight-Seeing Tour)

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.

zacharyz · Posted: Mon May 05, 2008 10:13 am Post subject:

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.

ksh · Posted: Tue May 06, 2008 12:49 am Post subject:

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?

Stuart Kovinsky · Posted: Tue May 06, 2008 9:32 am Post subject:

amitansu · Posted: Wed May 07, 2008 1:37 am Post subject:

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