Official Guide Explanation:
Data Sufficiency #49

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Solution and Metadata

Question: 49
Page: 156
Difficulty: 6 (Moderately Difficult)
Category 1: Arithmetic > Properties of Integers > Other

Explanation: Statement (1) is not sufficient. If r and s are integers, the number of possible values of n is 4, as in the example s = 6 and r = 1, where the possible values of n are 2, 3, 4, and 5. However, if r and s are not integers, the number of possible values of n is 5. For example, if r = 5.5 and s = 0.5, n could be 1, 2, 3, 4, and 5.

Statement (2) is not sufficient: without the range between r and s, you cannot find the answer.

Taken together, the statements are sufficient. If r and s are integers and the difference between them is 5, the number of possible values must be 4: s - 1, s - 2, s - 3, and s - 4. Choice (C) is correct.

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