String Series, Number B

The Puzzler

RAY: As promised, this is the second in a series of two string Puzzlers. You may remember the other Puzzler.

TOM: Two pieces of string, you burn something.

RAY: There you go. You have two pieces of string, and each of them will, if you light one end, will burn up in an hour's period of time.

TOM: But at an unpredictable rate.

RAY: At an unpredictable, nonlinear rate, so you can't say, "OK, look, I'm going to cut the thing in half and light one piece of it, and that's going to burn up in half an hour." All you know is that from beginning to end, the burn time is an hour. And the old Puzzler was: How could you measure a 15-minute period of time? And you did so by lighting three ends at once. The first piece burns up in half an hour, OK?

TOM: Because it's lighting from both ends.

RAY: Right. The second piece burns for, obviously, half an hour, because it's, what? Lit at the same time as the other two ends. And then what you do is, you light the fourth end as soon as the first two flame-fronts have met.

TOM: Boom. That's 15 minutes.

RAY: Yeah. So, now you're armed with the same two pieces of string, your Zippo lighter, and that's it. And the question is: How do you measure six minutes?

Think you know? Drop Ray a note!

[ Car Talk Puzzler ]

Support for Car Talk is provided by:

Donate Your Car,
Support Your NPR Station

...and get a tax break!

Get Started

Find a Mechanic

Promo tile

Rocket Fuel