Official Guide Explanation:
Problem Solving #64

Background

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Solution and Metadata

Question: 64
Page: 161
Difficulty: 4 (Moderately Easy)
Category 1: Word Problems > Discount >
Category 2: Arithmetic > Percents > Percent Change

Explanation: When working with percents like 10% and 5%, there's no faster method than mental math. Work through the steps one at a time: first, increase $10,000 by 10%. 10% of $10,000 is $1,000, so the new total is $11,000. Second, increase by 5%. 5% of $11,000 is $550 (half of $1,100), so the new total is $11,550. Last, decrease by 10%. 10% of $11,550 is $1,155, so the new total is $11,550 - $1,155 = $10,395, choice (B).

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