Practice GMAT Data Sufficiency Question
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If n is a positive integer, is n + 2 > z?
 z^{2} > n
 z – n < 0
Correct Answer: B

Evaluate Statement (1) alone.
 The smallest possible value of n is 1 since n is a positive integer and the smallest positive integer is 1
 You know that z^{2} > 1, which is the smallest possible value of n. Possible values of z include any number whose absolute value is greater than 1. This does not provide enough information to answer the question definitively. Consider the following examples.
If z = 10 and n = 1, two values that are permissible since (10)^{2} > 1, then the answer to the original question is yes since 1 + 2 > 10.
However, if z = 10 and n = 1, two values that are permissible since (10)^{2} > 1, then the answer to the original question is no since 1 + 2 is not greater than 10.
Statement (1) is NOT SUFFICIENT.

Evaluate Statement (2) alone.
 Statement (2) can be rearranged:
z  n < 0
z < n
Stated Differently: n > z
Since n is greater than z, n+2 will definitely be greater than z because n is a positive integer and it will only become larger.
In other words, let z = (a number less than n). You can be sure that n + 2 will definitely be greater than (a number less than n).
Statement (2) is SUFFICIENT.
 Statement (2) can be rearranged:
 Since Statement (1) alone is NOT SUFFICIENT and Statement (2) alone is SUFFICIENT, answer B is correct.
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