Official Guide Explanation:
Problem Solving #D09

Background

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Solution and Metadata

Question: D09
Page: 21
Difficulty: 6 (Moderately Difficult)
Category 1: Arithmetic > Descriptive Statistics > Average
Category 2: Arithmetic > Descriptive Statistics > Standard Deviation
Category 3: Arithmetic > Descriptive Statistics > other

Explanation: Consider each of the three measures. If 5 is added to each term, the mean increases by 5. The same happens to the median--whatever the middle number is, it increases by 5. The standard deviation, however, doesn't change. The SD depends on the difference between terms. If every term increases by 5, the difference between the terms doesn't change, so the SD stays the same. Choice (D) is correct.

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