IQ Test Labs

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practice questions

18. Bridge

Four hikers want to cross a rope bridge where only two can cross each time. It is already night, so one person has to return the torch after each trip. Each person takes different times to walk across once: 5, 10, 20, & 25 minutes. What is the least amount of time necessary for everyone to cross?

Each pair is moving at the speed of the slowest person.

The 20 and 25 minutes hikers should cross together,
and neither of the two should return.

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