A clever video puzzle to keep your brain active on a Friday. You’re a wizard and you’re making a potion. It needs to be stirred after exactly 45 minutes, no earlier and no later, or else it will be ruined. You have no clock or timer, but you do have two fuses of irregular consistency, each of which takes one hour to burn from one end to the other. How do you know when to stir your potion? Pause the video at the 4:30 mark if you don’t want to hear the answer.

I have to admit that a lifetime of listening to National Public Radio’s Car Talk program, with its weekly “Puzzler” segment, had me well prepared to figure this out. How did you do?

David Crotty

David Crotty

David Crotty is the Editorial Director, Journals Policy for Oxford University Press. He serves on the Board of Directors for the STM Association, the Society for Scholarly Publishing and CHOR, Inc. David received his PhD in Genetics from Columbia University and did developmental neuroscience research at Caltech before moving from the bench to publishing.

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5 Thoughts on "Friday Potion Puzzler"

mark the fuse into quarters and stir the potion when 3/4 have burned. My guess.

Nope — the fuses are made of mixed materials and each particular segment may burn at a different rate. All you know is that the whole thing takes an hour to burn.

I hate to admit it, but I don’t quite get the explanation. (But I won’t go into it here because spoilers.)

You can’t rely on the fuses, but if I’m a wizard I’d be used to mixing potions and would rely on my intuition for knowing when to stir? 🙂

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