Gary Foshee walked to the lectern to present his talk. It consisted of the following three sentences: “I have two children. One is a boy born on a Tuesday. What is the probability I have two boys?”

The Christmas Day bomber, Umar Farouk Abdulmutallab, has been indicted by a US grand jury on a charge of “attempted use of a weapon of mass destruction”. Yes, that’s right, a pair of loaded underpants is now officially a WMD.

Inside a windowless room is a light that is off. There are three switches outside, only one of which turns the light on/off. You are outside the room and allowed to play with the switches but not to look into the room in the process. You are allowed to go into the room once, after which you must directly say which switch works the light?

Looking at a usual analogue clock, how many times does the minute hand pass the hour hand between midday and midnight?

You have a full champagne bottle and only a ruler for measuring. How do you calculate the volume of the bottle?

Three logicians have all managed to sleight each other (don’t ask) and they meet for a three-way pistol duel at dawn.

A glass of gin and a glass of tonic stand side by side. Take a measure (eg, a thimble) from the gin glass and empty it completely into the tonic glass. Then fill the measure again from the tonic glass and pour it out completely into the gin glass. Does the gin contain more tonic than the tonic contains gin?

I don’t know about you, but I find that most of the pie charts in most of the presentations I see are really hard to read. But here’s one packed with insight...