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Last Updated on May 10, 2023
GMAT OFFICIAL GUIDE DS
Solution:
We need to determine whether n is an integer.
Statement One Alone:
n^2 is an integer.
If n^2 is an integer, n could be an integer or a non-integer. For instance, if n^2 = 4, then n is an integer (since n = 2 or -2). However, if n^2 = 5, then n is not an integer (since n = √5 or -√5).
Statement one is not sufficient to answer the question. We can eliminate answer choices A and D.
Statement Two Alone:
√n is an integer.
In order for √n to be an integer, n must be an integer. This is because n = (√n)^2 and any integer, when it is squared, is also an integer. Statement two is sufficient to answer the question.
Answer: B
