September 2009
9 posts
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Answer: Tuesday Teaser #4
Problems like this are always worth illustrating with diagrams. We’ll label the two chambers that contain bullets in red and the empty chambers in grey. Because Bob didn’t blow his brains out, he must have fired from one of the four grey chambers. Now for three of these chambers, the next chamber to be fired will be empty, so we have a 3/4 chance of surviving if we keep the arrangement...
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Tuesday Teaser #4
Imagine that you’re playing Russian Roulette with your arch-nemesis Bob. The gun that you’re using has a standard circular barrel, containing six chambers. Bob places two bullets in consecutive chambers and spins the barrel. He puts the gun to his head and pulls the trigger. He gets lucky.
Now it’s your turn. Before you pull the trigger, you can spin the barrel or you can leave...
“I will be your Ark,
We will float above the storm
—”
– from Ticket Taker by The Low Anthem
Listen
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Answer: Tuesday Teaser #3
This is a classic in that it’s easy to solve if you think about it in the right way, but very difficult if you start thinking about it the wrong way. When I first heard this puzzle I started thinking that there might be a situation where one ant keeps bumping into other ants and ends up staying on the stick for a long period of time. My girlfriend, on the other hand, got the answer straight...
“I will not cease from mental fight
Nor shall my sword sleep in my hand...”
– William Blake
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Tuesday Teaser #3
I have a stick that is one metre long. On that stick there are 10 randomly-placed ants, each of which starts to move towards one of the ends of the stick (at random) at the constant speed of 1 metre per minute. When two ants collide head-on, they both change direction immediately (i.e. they bounce off each other) and carry on at the same speed. When an ant reaches one of the ends of the stick, it...
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