GMATPrep - Practice Test #1 - DS - Please Help

dominate11

Any insight would be much appreciated...

7. In the triangle ABC above, what is the length of side BC? 1) Line segment AD has length 6 2) x=36 ( I was not sure how to include the example of the triangle)

9. On the 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.

gabriel

Stacey Koprince · Posted: Sun Mar 11, 2007 10:52 pm Post subject:

Hi, dominate - if you don't know how to post images, you can also just describe the triangle in text.

Mark Dabral

Here is the problem from GMATPrep. This problem is also in OG11, and I believe there is a typo in the book. The problem as stated here is correct.

Cheers,
Mark

snapplesf · Posted: Tue Mar 13, 2007 10:54 pm Post subject: triangle ABC

Hi dominate11 ,

Assuming you figured out the triangle problem. if not,

if you work out the angles, you see that angles BAD=ABD
hence sides AD=BD=BC - hence A is sufficient.

hengirl03 · Posted: Mon Sep 08, 2008 11:18 pm Post subject:

Would someone please post a detailed explanation to this problem? I'm still confused. Thanks!

Stacey Koprince · Posted: Tue Sep 09, 2008 5:59 am Post subject:

they ask for a length, so statement 2 is not going to be useful - it gives us an angle only, and you can have a triangle of any size, teeny-tiny to huge, with those angles.

So, ACE.

AD is 6. <BAD is x. <BCD is 2x. <BCD is 2x. They want to know side BC.

<BDC is what's called an exterior angle of triangle BAD. You create this by taking any leg and just extending it out in a straight line. That exterior angle is always equal to the sum of the two opposite interior angles - in this case, angles BAD and ABD. So BAD + ABD = BDC. Fill in what you know. x + ABD = 2x. Solve. ABD = x.

So if ABD = x, it's the same angle as BAD. This means the sides opposite these angles are the same also. We know AD is 6, so BD is also 6.

Now look at the triangle on the right. We also have two identical angles there, so the two opposite sides are the same. One of those sides is BD (which we already know is 6) and the other side is BC, which we want to find. BC is also 6.

So statement 1 is sufficient. Answer is A.

hengirl03 · Posted: Tue Sep 09, 2008 10:16 am Post subject:

Thanks Stacey!

canuckclint · Posted: Thu Sep 11, 2008 9:01 pm Post subject:

For triangle ABD,
x + angleB + (180-2X) = 180
angleB - x = 0
angleB = x

The right triange is isoceles and you can go from there.