How many person-hours are spent listening to graduation speeches each year? How long is this in lifetimes?

If we are stuck in the middle of a 100-m radius frozen (i.e., frictionless) lake, how long would it take us to escape, using just a small handheld, electric fan?

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Question suggestions are always welcome!

For more Fermi questions and answers, see Guesstimation 2.0: Solving Today’s Problems on the Back of a Napkin, by Lawrence Weinstein (Princeton University Press, 2012).

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