PowerPrep...number line DS question

erjamit

Hi,

Pls answer the powerprep question. I think I am overlooking some information here.

Thanks
Amit

gxliu · Posted: Mon Jun 30, 2008 10:34 am Post subject:

draw a line..and come up with diff possibilities..
C is the answer.

rosh26 · Posted: Mon Jun 30, 2008 2:08 pm Post subject:

I would guess E...what is OA?

atlantic · Posted: Tue Jul 01, 2008 1:07 am Post subject:

Hi erjamit,

I would go with E also.

The statement says mod(A-B)=18 and mod(c-d)=8, what is the mod(B-D)?

(1) mod(C-A)=mod(C-B)
you get A=B or A+B=2C, INSUFF

(2) gives no relevant information concerning the question, INSUFF

(1+2) nothing new, INSUFF

Answer E

erjamit · Posted: Sun Jul 06, 2008 1:36 am Post subject:

OA is E.

erjamit · Posted: Sun Jul 06, 2008 1:52 am Post subject:

I will illustrate as following:-

From the question stem:-

A ---------------------------------------- B = 18

or

B ---------------------------------------- A = 18

and CD = 8.

1) CA = CB => C is the mid-point of A.

2 scenarios can come here...

A ------------------C---------------------- B = 18

or

B -------------------C--------------------- A = 18

Insuff...

2) A is to left of D.
Insuff..

Combining 1 and 2.

A ----D---------------C--------------------- B

or

B ---------------------C------------------A---D

The 2nd figure contradicts CD = 8 since CA = 9 and CD = 8. Thus, the only valid figure is 1st one.

So, IMO answer should be C.

Can someone pls comment what mistake I am making.

Thanks
Amit

ildude02 · Posted: Sun Jul 06, 2008 9:10 am Post subject:

erjamit,

You are right that the second chouce is not valid, But you could consider an other option like this,

A---------------C-----------D---B; this would still satify that A is to the left of D

Bt you could see that the BD distance is now 9-8 =1; and from the first figure you drew, we got BD as 9 + 8= 17; so it's insifficient.
All statement 2 says is, A is of lower value then D, since on a number line, any point which is left to an other point is of lower value than the point to the right.

erjamit · Posted: Tue Jul 08, 2008 11:53 pm Post subject:

I got it what mistake I was making.

Thanks
Amit