DS Practice test question #15

It should be A -

let me know OA - then I'll explain

My answer to this is C. See explanation below

First ANALYSE the QUESTION STEM. In particular note that there is no information given about p or r. They can be negative numbers, they can be fractions etc ... it doesnt say anything about them being positives or integers.
If you dont take note of this you can fall into choosing the trap answer A.

Also note that the inequality can be simplified:
1/p > r/(r^2 + 2)
1/p > r/(rr+2)
1/p > 1/(r+2)

(1) p = r
so lets replace the r with p in the inequalty 1/p > 1/(r+2)
This becomes to: 1/p > 1/(p+2)

It would appear that this would provide SUFF information to solve, but lets double check by considering 2 scenarios:
1) let p = positive fraction... say 1/4.
so we have: 1/(1/4) > 1/(1/4 + 2)
becomes: 4 > 4/9 ... and we can answer YES to this question. 4 is greater than a 4/9.
2) let p = negative fraction ... say -(1/4).
so we have 1/-(1/4) > 1/(-(1/4)+2)
this becomes -4 > 4/7 ... and we can answer NO to this question. -4 is NOT greater than 4/7.

So hence (1) is INSUFF to answer the question.

(2) r>0 is INSUFF since it provide no details about p.

(1) and (2) together is SUFF because statement (2) rules out the possibility of the negative values (in our example the negative fraction).

So I guess the key take-away from this is to make a note of what info IS provided in q-stem and what is NOT provided.

But then again ... I may be totally wrong here ... whats the official answer here?

Thanks.
II

I agree with II answer has to be C. I'll be really surprised if the answer is E.

Since r>0 => 1/r > r/r^2+2

Whats the OA?

II wrote:My answer to this is C. See explanation below

First ANALYSE the QUESTION STEM. In particular note that there is no information given about p or r. They can be negative numbers, they can be fractions etc ... it doesnt say anything about them being positives or integers.
If you dont take note of this you can fall into choosing the trap answer A.

Also note that the inequality can be simplified:
1/p > r/(r^2 + 2)
1/p > r/(rr+2)
1/p > 1/(r+2)

(1) p = r
so lets replace the r with p in the inequalty 1/p > 1/(r+2)
This becomes to: 1/p > 1/(p+2)

It would appear that this would provide SUFF information to solve, but lets double check by considering 2 scenarios:
1) let p = positive fraction... say 1/4.
so we have: 1/(1/4) > 1/(1/4 + 2)
becomes: 4 > 4/9 ... and we can answer YES to this question. 4 is greater than a 4/9.
2) let p = negative fraction ... say -(1/4).
so we have 1/-(1/4) > 1/(-(1/4)+2)
this becomes -4 > 4/7 ... and we can answer NO to this question. -4 is NOT greater than 4/7.

So hence (1) is INSUFF to answer the question.

(2) r>0 is INSUFF since it provide no details about p.

(1) and (2) together is SUFF because statement (2) rules out the possibility of the negative values (in our example the negative fraction).

So I guess the key take-away from this is to make a note of what info IS provided in q-stem and what is NOT provided.

But then again ... I may be totally wrong here ... whats the official answer here?

Thanks.
II

Hey this part is not right
-------------------------------------
Also note that the inequality can be simplified:
1/p > r/(r^2 + 2)
1/p > r/(rr+2)
1/p > 1/(r+2)
-------------------------------------

it will become
1/p > 1/(r + {2/r})

whats the OA ?