gmat prep DS

IMO E

navalpike wrote:On the number line, the distance between point A and point C is 5 and the distance between point B and point C is 20. Does point C lie between point A and B?

1. The distance between point A and point B is 25.

2. Point A lies to the left of point B.

info given:

a-5-c and b-20-c

only combos that work for c to be in middle are:

a-5-c-20-b or b-20-c-5-a

statement 1)

if a-b=25 there is no way that b-c=20 and a-c=5 without c being in middle.

sufficient

statement 2)

if a <b there is no way b-c=20 and a-c=5 without c being in middle.

sufficient

D

you got this!

plz confirm

I would go with A
please let me know if i am right .

I would also go with A.

I go with D...


In the question they have given only the distance between the points...

the points can be such as C<-5units->A<-15Units->B

or the points can be A<-5units->C<-20Units->B

Statement I shows that the distance between the points A and B is 25, so the points are as given below
A<-5units->C<-20Units->B
Hence sufficient

StatementII shows A is to the left of B. So the points are as given below:
C<-5units->A<-15Units->B
Hence sufficient.

So the answer is D :roll:

In case of statement 2, A can be left to B in both the scenarios:
A <5 Units> C <20 Units> B
C <5 Units> A <15 Units> B

In first case, C lies between A and B, and in second case it is not. So, B is not sufficient.

I go with A....

Whats the OA?

Please post the solution after you post the question. Else it would be a waste of effort for most of us.

C is not in between A and B with statementII .
But we are able to get the answer that C is not between A and B.
So statement II is sufficient to answer the question "is C in between a and B?"
In Data Sufficiency, we have to check if we can answer the question and not if we get the expected answer...

OA is A

Thanks for the responses. However, in the above responses, sadly, I do not see anything that will help me on the actual exam. The correct answers are without an explanation and rest are incorrect.

Can you kindly show me "how to approach" this type of problem on the exam?

Thanks in advance

navalpike wrote:OA is A

Thanks for the responses. However, in the above responses, sadly, I do not see anything that will help me on the actual exam. The correct answers are without an explanation and rest are incorrect.

Can you kindly show me "how to approach" this type of problem on the exam?

Thanks in advance

You can come out with 4 scenarios based on the info in the question stem. Giving an idea below.

1. A C B

2. B A C

3. C A B

4. B C A

Now go to question stems and evaluate. HTH

Hi, IMO A.

I approached this question by drawing a number line and position each point in order to determine whether the scenario given in the question stem help me to determine the relative position of C to the positions of A & B.

I started with stmt 1.

Since the distance between A & C is 5 and the distance between B & C is 20. We know that C is closer to A than it is to B.

I started with A in the middle and B to A's right & C to A's left. I quickly realized that this position of C will not meet the criteria that the difference b/w B & C is 20 given the distance b/w A & B is 25.

If C-----A (5, the distance between C & A as given)-----A---------B (25)
then C--------B can't equal to 20

Therefor C-A-B out

Then I tried B in the middle and A to its left and C to its right:


A---------(25) B---------C (20) here you can see that there is no way that the distance betweem A & C is 5


Therefore the only option is to put C in the middle:


A-----(5) C-------(20) B and this agrees with stmt 1 that distance b/w A & B is 25


Stmt 2 it only gives the position of A in relations to B however, it does not give us any other information.

Furthermore, since we are always required to have 3 distint linear equation to solve for the values of 3 distint unknown variables, I believe another unique equation is necessary to determine the placement of C.

Therefore, I choose A.

I don't know if this is the most time efficient way but this is how I obtained my answer.

I hope this helps you.