Official Guide Explanation:
Data Sufficiency #71




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Solution and Metadata

Question: 71
Page: 158
Difficulty: 5 (Moderate)
Category 1: Arithmetic > Ratio and Proportion >
Category 2: Word Problems > Rate Problems > Speed

Explanation: Statement (1) is sufficient: if Betty's trip would've taken 2 hours at 1.5 times her actual rate, the distance is equal to (rate)(time) = (1.5r)(2). Since the distance is the same regardless of speed, her actual (rate)(time) = rt is equal to (1.5r)(2). So, rt = (1.5r)(2), or t = 3.

Statement (2) is insufficient: given average speed, you would also need distance to calculate time. The correct choice is (A).

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