Archive for April, 2009

A sweet paradox

Thursday, April 30th, 2009

A frined of mine likes sweets. To be precise, he likes sweets of different tastes. Once he bought four sweets, two strawberry and two lemon.

- How many sweets will you eat? I asked.
- Just two. And I hope they are of different taste.
- Well, they may be, you know. If you are lucky.
- What do you mean?
- Well, if you pick two sweets at random there are 4 possible ways of doing it, and 2 of these have different tastes. 
- So you are saying that my chances are 1/2?
- Exactly.
- I have found a better way!
- Really?
- I eat one sweet, it doesn’t matter which.
- And then?
- Of the three remaining sweets 2 have a different taste than the first so my chances are 2/3 for getting two sweets of different taste.
- You must be a genius. I thought 1/2 was all you could hope for.

Problem source: Activa sus neurona by laberintos e infinitos.

Almost a quote

Thursday, April 30th, 2009

Bread isn’t made by early risers. It’s made by lazy men trying to find easier ways to do something. - Robert Heinlein

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

Squeeze it

Wednesday, April 29th, 2009

A wet sponge weighs 1kg and 99% of its weight is water. Squeeze it till 98% of its weight is water. How much does it weigh now?

Problem source: Activa sus neurona by laberintos e infinitos.

Almost a quote

Wednesday, April 29th, 2009

Humor is just another defense against the mathematicians. - Mel Brooks

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

Searching for Marilyn Monroe

Tuesday, April 28th, 2009

If in a country 60% are women, 70% have blue eyes, and 80% are blondes, what is the smallest possible percentage of the population who are blue eyed, blonde, women?

Problem source: Activa tus neuronas by laberintos e infinitos.

Almost a quote

Tuesday, April 28th, 2009

It was on my fifth birthday that Papa put his hand on my shoulder and said, ‘Remember, my son, if you ever need a helping hand, you’ll find one at the end of your life.’ - Sam Levenson

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

Find the spelling mistake

Monday, April 27th, 2009

I cdnuolt blveiee taht I cluod aulaclty uesdnatnrd waht I was rdanieg. The phaonmneal pweor of the hmuan mnid, aoccdrnig to a rscheearch at Cmabrigde Uinervtisy, it deosn’t mttaer in waht oredr the ltteers in a wrod are, the olny iprmoatnt tihng is taht the frist and lsat ltteer be in the rghit pclae. The rset can be a taotl mses and you can sitll raed it wouthit a porbeml. Tihs is bcuseae the huamn mnid deos not raed ervey lteter by istlef, but the wrod as a wlohe. Amzanig huh? yaeh and I awlyas tghuhot slpeling was ipmorantt!

Almost a quote

Monday, April 27th, 2009

The pursuit of happiness is a most ridiculous phrase; if you pursue happiness you’ll never find Rome.- C. P. Snow

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

Reflections

Sunday, April 26th, 2009

- Hello, is this the math department?
- Yes, speaking. Who is calling?
- A politician.
- A politician? Nice of you to call! You do not call every day, so it is extra nice when you do. What may I do for you?
- I need a number.
- How is 5?
- No, that won’t do. I need a number for every country in the world.
- And 5 won’t do?
- The number should reflect how income or wealth is distributed in the country.
- I see.
- 0% means it is equally distributed and 100% that is far from it.
- To calculate such a number will not be easy.
- I don’t care.
- And it has to be taken with a grain of salt. 
- I don’t care.
- In some cases it may be misleading.
- I don’t care.
- Then I have the number for you.
- Really? That is great!
- The number is called the Gini coefficient
- What is the Gini number for Denmark and Namibia?
- 23.2% and 70.7%.
- That makes sense. I guess income is more evenly distributed in a Nordic country than one in Africa. 
- Glad the number fits in with your prejudices.
- How is the Gini number in the US evolving? Is it going up or down?
- You don’t want to know.

Playful thinking

Saturday, April 25th, 2009

Drag the circles and have some fun here.