How much excrement is produced yearly by all the animals we eat in the United States?

How much power is needed in the U.S. for all of the traffic signals (red/yellow/green lights)? (Thanks to Evan Jones, Sierra College, Emeritus, for providing the question and the answer.)

Look for the answers online at under “Browse,” at the very end of the current issue.

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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