Which Switch Switches?

The Puzzler

RAY: Well, here's the answer.

TOM: Yeah.

RAY: You turn the first switch on. You leave it on for ten minutes. Why, you ask? You'll see in a minute. Then you turn it off and you turn the second switch on and you go upstairs.

TOM: And you leave the third switch in the off position.

RAY: There you go.

TOM: Yeah.

RAY: If the bulb is on, then it's switch number two, which is the one that's on.

TOM: Right.

RAY: OK? If the bulb is off and it's cold, then it's switch number three, which is the one you never touched, that controls that light. If the bulb is off but it's hot, then it was switch number one.

TOM: Excellent.

RAY: Pretty cool, huh?

TOM: This is an excellent, this qualifies as an excellent puzzler. 'Cause it seems so impossible. This is a Martin Gardner puzzler.

RAY: It's right up there.

TOM: It's right up there.

RAY: It's right up there with one of his. Who's our winner this week?

TOM: Chip Merrow from Loudon, New Hampshire.

[ 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