John Tierney, New York Times
Now, on Easter Monday, we have a seasonal yet nondenominational puzzle involving a bunny rabbit — the “Killer Rabbit,” as the press dubbed it, that tried to board President Jimmy Carter’s boat as he was fishing at a pond in Plains, Georgia, in 1979. (Mr. Carter’s account of using his oars to fend off the hissing rabbit was mocked at the time, but eventually the White House released photos showing the incident and the swimming rabbit.) Here’s the puzzle:
Suppose, the day after attacking President Carter, the rabbit finds itself alone in the middle of the pond, which is perfectly circular. Suppose there is a single Secret Service agent on the edge of the pond, armed with a small net to ensnare the swimming rabbit as it approaches the edge. This net is effective only if the rabbit is still in the water. If the rabbit reaches any point on the edge before the agent does, it can hop away to freedom; if the agent gets there first, the rabbit will be captured.
If the agent runs four times as fast as the rabbit swims, can the rabbit escape? If so, how?
For extra credit: WhatÂ’s the fastest the agent can run (as a multiple of the rabbitÂ’s speed) such that the rabbit can still escape?
If youÂ’re stumped by the first question, you can get a hint or two by clicking here. |