# Category Archives: puzzles

## Friday puzzle: animals

Today’s puzzle:  How many animals do I have if all but 3 are dogs, all but 3 are cats, all but 3 are pigs and all but 3 are cows? Last week’s puzzle was getting U2 onto the stage in … Continue reading

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## Friday puzzle: U2

U2 has a concert that starts in just 17 minutes and all of the band members must all cross a bridge to get to the stage. The four men begin on the same side of the bridge and you must … Continue reading

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## Friday puzzle: states

Today’s puzzle is a word puzzle: find a pair of US states whose letters can be mixed together and re-arranged to make a different pair of US states. Last week’s puzzle was the cucumbers drying in the sun. There were … Continue reading

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## Friday puzzle: cucumbers

Today’s problem: on a sunny day a greengrocer places 200 lbs of cucumbers in front of his store. At the start of the day they are 99% water. He doesn’t sell any all day but it is a really hot … Continue reading

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## Friday puzzle: Monty Hall

Last week’s puzzle was the camel and the bananas. Firstly, a moment’s thought shows that the camel can’t get any bananas to market in one go. It is 1000 km away and so the camel will eat all of its … Continue reading

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## Friday puzzle: bananas

Last week’s puzzle was to estimate when the 20th record year of rainfall will occur in New York. The answer is in 272 million years time. In 1835 that year was a record year by definition. In 1836 there were … Continue reading

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## Friday puzzle: rainfall records

Last week’s puzzle was the toenail cancer test. The correct answer is that your chance of having toenail cancer is just under 1.9% obtained as follows. Of 20,000 people, 20 have toenail cancer (1 in 1000). Of those 20, 19 … Continue reading

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## Friday puzzle: toenail cancer

Last week you were asked about an ordering of numbers from 0 to 100. The answer is that they were in alphabetical order, starting with “eight,” “eighteen” and ending with “two,” “zero.” Don’t worry if you didn’t get it or … Continue reading

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## Friday puzzle: zero to one hundred

Last week’s puzzle was where Lisa asks me some questions about my house number. The first thing to note is that since Lisa knows the number if she is told whether the first digit is a 3 or not, then … Continue reading

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## Friday puzzle: house number

Last week’s puzzle was to try and find the train in the Nullarbor Plain, given that we know the direction of a train whistle we just heard. A couple of idealizations to make this truly mathematical: the train is a … Continue reading

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