String Series, Number A
RAY: And I did mention, I think, that there are two answers to this. I'm only going to give you one answer this week.
TOM: Oh, you are?
RAY: Yes, because the other answer is, well, in the future.
RAY: So, you take String A, light both of its ends. You take String 2, and light one end. Well, what's going to happen? Because you lit both ends of the first string, in a half an hour's time, that string is going to burn up completely. A half an hour has gone by, and similarly, the other string you lit is going to burn for: half an hour's time. Right?
RAY: At which point, as soon as the first string has burned up completely, you'll light the remaining end of String 2, and because the first part of that string you lit is continuing to burn, it's going to take 15 minutes before those two flame fronts meet, and you'll have measured 15 minutes from the time that you lit the second string.
TOM: Exactly. So, the question could have been, how would you measure 45 minutes? Or 15 minutes, and it would be the same answer.
RAY: Exactly. Who's our winner this week?
TOM: The winner this week is Calvin Kuhnen from Columbus, Ohio.
[ Car Talk Puzzler ]