## Archive for April, 2009

### No match for you

Friday, April 24th, 2009

Nob Yoshigahara wants you to move two matches so that no triangle remains.

Problem source: Creative Puzzle Thinking by Nob Yoshigahara  taken from the free book The mathemagician and the pied puzzler.

### Almost a quote

Friday, April 24th, 2009

History is the version of French events that people have decided to agree upon. – Napoleon Bonaparte

A word has been added or deleted, or replaced by another word, to arrive at the ‘almost a quote’ above. Which word?

### The hourglass problem 43 years later

Thursday, April 23rd, 2009

An unusual toy is on sale at a Paris shop: a glass cylinder, filled with water, and at the top an hourglass floats. If the cylinder is inverted a curious thing happens; the hour-glass remains at the bottom of the cylinder until a certain quantity of sand has flowed into its lower compartment. Then it rises slowly to the top. It seems impossible that a transfer of sand from top to bottom of the hourglass would have any effect on its overall buoyancy. Can you guess the simple modus operandi?

This problem, The Floating Hourglass,  was one of the problems in Martin Gardner’s August 1966 “Mathematical Games”.

Can you solve it?

Read this fascinating tale about the problem: Beautiful but Wrong: The Floating Hourglass Puzzle by Scot Morris taken from the free book The mathemagician and the pied puzzler.

### Almost a quote

Thursday, April 23rd, 2009

Often it does seem a pity that Noah and his party did not miss the train. – Mark Twain

A word has been added or deleted, or replaced by another word, to arrive at the ‘almost a quote’ above. Which word?

### Excessive reasoning

Wednesday, April 22nd, 2009

– Take two positive numbers and call them x and y. Let one of them be twice as big as the other, but we do not know which.
– But we are going to find out?
– I will prove to you that if y is the bigger number then its excess over x is bigger than the excess over y x would have if x was the bigger number.
– Would you like fries with that?
– Suppose y is greater than x. Then y = 2x and y’s excess over x is obviously x (2x – x = x).
– I get scared when I hear the word ‘obviously’.
– On the other hand, if x is greater than y, then y = x/2 and the excess is  x/2 (x – x/2 = x/2).
– So what?
– Since x is greater than x/2 I have just shown that if y is the bigger number than the excess is bigger than if x is the bigger number.
– But, that can’t be!
– I will give you a simple example as letters seem to confuse you.
– Much obliged.
– If x is 100 than the excess if x is bigger is 50, but if x is smaller the excess is 100. In other words, if y is bigger the excess is more.
– I got a headache.

Problem source: A Curious Paradox, by Raymond Smullyan taken from the free book The mathemagician and the pied puzzler.

### Almost a quote

Wednesday, April 22nd, 2009

Free advice is worth half the price. – Robert Half

A word has been added or deleted, or replaced by another word, to arrive at the ‘almost a quote’ above. Which word?

### Buffaloes in a boat with tigers

Tuesday, April 21st, 2009

– Here is a practical problem if ever there was one.
– It was about time! Many of the problems in this blog are just artificial constructions unable to increase the tomato harvest.
– “Three tigers, A, B, C and three buffaloes, X, Y, Z have to cross a river with a boat that can only take two.”
– Since when did animals use a boat?
– “Only A and X knows how to steer the boat.”
– Tigers can steer a boat?
– “Any time tigers outnumber the buffaloes at either side of the river, they will attack and kill the buffaloes.”
– That may be true. Who am I to know.
– How did they do it?
– Did what?
– Cross the river.

Problem source: Engin Demirsecen in the LinkedIn group Math, Math Education, Math Culture.

### Almost a quote

Tuesday, April 21st, 2009

A billion here, a billion there, pretty soon it adds up to my money. – Senator Everett Dirksen

A word has been added or deleted, or replaced by another word, to arrive at the ‘almost a quote’ above. Which word?

### Walk slowly

Monday, April 20th, 2009

Five people come to a bridge in the jungle at night time. They have a torch to see their way over the bridge, but it will only last another 30 minutes.

They all need different times to cross the bridge: 1, 3, 6, 8, and 12 minutes. Only two can walk on the bridge at the same time. When two are walking they have to walk at the slowest speed.

How do they cross?

Problem source: Engin Demirsecen in the LinkedIn group Math, Math Education, Math Culture.

### Almost a quote

Monday, April 20th, 2009

If the only tool you have is a hammer, you tend to see every nail as a nail. – Abraham Maslow

A word has been added or deleted, or replaced by another word, to arrive at the ‘almost a quote’ above. Which word?