Official Guide Explanation:
Problem Solving #22




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Solution and Metadata

Question: 22
Page: 64
Difficulty: 5 (Moderate)
Category 1: Word Problems > Measurement Problems >
Category 2: Arithmetic > Powers and Roots of Numbers > Powers

Explanation: "Double" is another way of saying "multiply by two," so each time the population doubles, it's multiplied by 2. Since it doubles six times (once per ten minutes for an hour, or sixty minutes), the population is multiplied by 2(2)(2)(2)(2)(2), or 26. The original population was 104, so the population an hour later is 104 * 26, choice (C).

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