Official Guide Explanation:
Problem Solving #110

Background

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Solution and Metadata

Question: 110
Page: 75
Difficulty: 7 (Very Difficult)
Category 1: Arithmetic > Ratio and Proportion >
Category 2: Word Problems > Rate Problems > other

Explanation: At 6:00, there are six strokes. The key to this question is recognizing that there are not six between - stroke intervals. There is an interval after each stroke, except for the last. So the number of intervals will always be one less than the number of strokes. So, at 6:00, there are six strokes and five intervals, each of which are equal in length. If the 11 strokes and intervals take 22 seconds, each stroke or interval must require (22/11) = 2 seconds. At 12:00, there are 12 strokes and 11 intervals, for a total of 23 2 - second events. The amount of time required, then, is 23(2) = 46 seconds, choice (D).

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