Official Guide Explanation:
Data Sufficiency #129

Background

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Solution and Metadata

Question: 129
Page: 284
Difficulty: 5 (Moderate)
Category 1: Arithmetic > Descriptive Statistics > other
Category 2: Arithmetic > Percents > other

Explanation: Statement (1) is insufficient. If 25 percent of the projects have 4 or more people, then 75 percent of the projects have 3 or fewer people. The median is somewhere in that 75 percent (it's between the 49th and 51st percent, to be exact), but we don't know whether that's 1, 2, or 3 people.

Statement (2) is also insufficient. By the same reasoning, if 35 percent have 2 or fewer employees, 65 percent have 3 or more. The median is somewhere between 3 and a very large number, but we don't know where.

Taken together, the statements are sufficient. The statements leave us with a middle 40 percent of projects that have both 3 or fewer people and 3 or more people assigned to them. Put it all together, and all of those middle 40 percent of projects have exactly 3 people assigned to them. Since we're talking about the middle 40 percent, the median must be 3. Choice (C) is correct.

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