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Nine minutes with a 4 and a 7 minute glass

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You have a 4-minute hourglass and a 7-minute hourglass. An egg goes into boiling water right now, and it must come out after exactly 9 minutes.

Describe the sequence of flips. You may flip a glass at any moment, including while it is still running.

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Seven plus one plus one is nine. Can you produce a one-minute timer twice?

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