Official Guide Explanation:
Problem Solving #168

Background

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Solution and Metadata

Question: 168
Page: 84
Difficulty: 6 (Moderately Difficult)
Category 1: Arithmetic > Ratio and Proportion >
Category 2: Arithmetic > Fractions >
Category 3: Word Problems > Rate Problems > other

Explanation: Since flights leave A every hour and take 2(1/2) hours to reach their destination, they arrive on the half - hour, starting at 10:30. Flights leave B every 20 minutes, so no matter what hour the passenger arrives, the passenger will only have to wait 10 minutes before getting on a flight at forty minutes past the hour. If she departs at forty minutes past the hour, she'll arrive 1(1/6) hours (one hour and ten minutes) later, at fifty minutes past the next hour. Flights only leave C at 45 minutes past the hour, so she'll have to wait 55 minutes. Total wait? 10 + 55 = 65 = 1 hour, 5 minutes, choice (B).

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