Official Guide Explanation:
Data Sufficiency #59




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Solution and Metadata

Question: 59
Page: 157
Difficulty: 6 (Moderately Difficult)
Category 1: Word Problems > Rate Problems > Speed
Category 2: Geometry > Circles > other

Explanation: Given the number of rotations is equal to the length (100 meters) divided by the length per rotation. In other words, we need the length per rotation to solve. Statement (1) is sufficient: the length per rotation is the circumference of the wheel, and with the diameter, you can find the radius, and with the radius you can find the circumference. Statement (2) is not sufficient: we're looking for the length per rotation, not the time per rotation. Choice (A) is correct.

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