Wrong Number

Thirteen percent of the people in San Diego have unlisted phone numbers. You select three hundred names as random from the phonebook. What is the expected number of people who have unlisted numbers?

Why does Rocket Go Up ?

Professor Feynman was teaching the class.
"Even from students of physics one may often hear a totally wrong explanation of a rocket's flight. They claim that it goes up by thrusting itself away from the air with the help of gases formed from gunpowder combustion. That incidentally is what ancients thought-rockets are invented long, long ago."

He added "But if we were to fire a rocket in an airless void it would fly, and even better than in the air."

What's the right explanation ?

Money Lender

Jack and Johnny are sitting alone at a table. Johnny is broke. Jack aggrees to lend Johnny $186 consisting one each of $100, $50, $20, $10, $5 and $1 doller bills, if Johnny can determine how the money is passed to him given the following rules:

1. Only 1 bill may be passed at a time.

2. A bill may be passed from passed from Jack to Johnny, from Johnny to Jack, or placed on or taken from the table by either Jack or Johnny.

3. 0nly the smallest bill held can be passed or taken. (ie jack cannot get rid of the $5 if he has the $1 also. Johnny cannot take the $10 from the table if the table also has the $5 or the $1)

4. Jack, Johnny and the table can only receive a bill if they do not have a smaller bill already. (ie. if Johnny has the $10, he can only receive the $5 or the $1.)

-Euclid's Brother

Japanese IQ quiz

Ok so instead of making my own puzzle I'll let you guys play a mind game

Ok the website for it is http://freeweb.siol.net/danej/riverIQGame.swf

Since the rules are in Japanese I'll tell you them:

Only the adults, The mom,dad, and Police officer, can Pilot the boat, the Dad is not to be left alone with any of the daughters without the Mom (the escaped Convict doesn't count), and The mom is not to be left alone with out the sons without the dad, The last rule is The Convict can not be without the police officer at all
(If you get something wrong it will give you a cutscreen to show you why you can't do that)
If you end up getting them all across the river, put down your steps (There are multiple ways it is succedable

Analogy

Complete the analogy. Example High is to low as sky is to /e/a/r/t/h/.
Skull is to brain as shell is to / / / / /.

A Traveler

A female traveler got lost in a jungle and was caught by a tribe of cannibals. As they tied her up, the cannibal leader said
"All right. We will let you say your last words.If your last words are a LIE, we will eat you ALIVE If your last words are TRUE, we will eat you COOKED"
And with that, the leader roared with laughter.
Now the witty traveler thought for a while and said her last words. After hearing the traveler's statement, the leader had no choice but to let her go. What did the traveler say?



by world_pride

Boat Crossing Problem

There's a group of 3 men and 3 Gs trying to cross a river. There's a boat available but it can take a max of 2. Only 1G knows rowing whilst all 3 men can row. Gs must not out number the men at any point including ones in boat/land. No restriction on number of trips.

Face Value

Why is 2008 quarters (25 cent coins) worth more than 2007 quarters?

Fantasy & Science Fiction

Isaac Asimov had a 30 years correspondence with Nobel Prize winner Linus Pauling. Pauling read Isaac's science articles in Fantasy & Science Fiction magazine regularly and wrote Isaac whenever he found an error. Here is an interesting excerpt.
From Pauling to Isaac:

I am writing now about your article in the September 1978 issue. On page 123, you say that Amontons and Guy-Lusac observed that if a gas at the freezing point of water, 0 degree Celcius, is decreased in temperature to -1 degree Celcius, then both the volume and the pressure of the gas will decline by 1/274 of the temperature. This is wrong. What you should have said is that _ _ _ I hope you are keeping busy as ever.

What was the explaination?

Longest Word !

Madam Query was late again. She saw always late chalked on the board. She became upset, "You all are very Impertinent and will not get any extra credits in English this year." She said.

"I can forgive you all in ONLY one condition. Tell me the longest word in English which does not repeat any letters?" Assume you were there, can you save your classmates ?

How old is his great-granddad

Just how old is your great-granddad?
Well, when he was 1/7 of his age plus one, he understood calculus.
When he was 1/5 of his age minus one, he mastered quantum mechanics.
When he was 1/3 of his age minus three, my granddad was born.
And when he was 1/2 his age plus five, my dad was born.

Multilingual

Steve was amazed by "the fact" that this is one thing in the world that can speak all languages ?

Would you know what ?

TomWebUser's Allowance

Tom was given his allowance last week, which is meant to last him all week. On Monday, he spent a quarter of his money on gambling. On Tuesday, he spent one third of the remaining money on games. On Wednesday he spent half of his remaining money on paying his bookie. Finally on Thursday he spent my last $1.25 on an adult magazine. How much allowance did he receive?

The A to G puzzle

Work out the numbers of A to G if...

A+B+C+D+E+F+G=340
3A+7B-4C-13D+E-6F+2G=219.25
2A-7B+9C-4D-3E+2F+3G=82
ABC=21,150
DE=1225.25
FG=3,145
BDF=11,544

Also C is the smallest number, and E is the biggest number. F is the middle number.

~Alexander

Minutes To Noon

How many minutes is it before 12 noon, if 55 minutes ago it was four times as many minutes past 9 AM.

Absolute Favorite Questions

Hey Guys,
A quick survey to find out what kind of question you like the most. Recently I added a new category for physics lovers "FunPhysics", hope you guys are having a bit of stretch-of-mind there. Here is a chance to get heard.



I would love to see, if you have any other comments.

- Rajesh

A Motorless Underground Railway

If you have read the free travel, you will find this more intriguing. A booklet with the odd title A Motor less Underground, Leningrad-Moscow Railway was once put out. Its author A.A. Rodnykh, suggested a very interesting project .

His idea was to "dig a 600-km-long tunnel, linking up two cities Leningrad and Moscow by an absolutely straight underground line. this could give us for the first time the opportunity to travel along the straight instead of following a curved path as now." He wishes to say that all our roads describes arcs, as they follow the curve of the earth surface, while the suggested tunnel will follow a straight line along a chord (assume earth as a circle).

This project - if ever realized - would possess a unique characteristic. In this tunnel a train move by itself. At each point, since the train is going in the downward direction due to gravity, it will not require a motor. The big tunnel will actually be inclined to some angle with the horizontal ground at both the points.

In such a slanting tunnel every object should swing, due to gravity, to and fro like a pendulum, hugging to the bottom. Inside it a train would move by itself along the rails, its weight doing the work of locomotive. At first the train will move very slowly but with every new second its speed would increase, to reach soon a figure so incredible,that the air in the tunnel would offer a noticeable resistance.

Do you see any flaw in this design, A motorless vehicle can help realize the dream of free travel. Why this is not done yet?

Silverfish Strikes Back

Silverfish gets this time into a sphere of radius 31 mm and digs a tunnel of total length 61 mm.

Can you cut the sphere with a straight slice through the center so that one of the two halves is not in the tunnel area?

* The tunnel need not be a straight line. Here is one old adventure of Silverfish

Persistence

A young salesman Good Benito was finally admitted to the office of the president, who chided him, "Young man, you should feel flattered that I allowed you to come in here. I turned down five salesman today.

"I Know" replied Good Benito . "_ ___ ___ ____ __ ____"

What did he said ?

The "Chess" Family

Viswanathan Anand, his sister, his son, and his daughter are chess players. The following facts refer to the people mentioned:

1. The best player's twin and the worst player are of opposite sex.
2. The best player and the worst player are of the same age.

Which one of the four player is the best player ?

what am I 3

I am not wet and I am not dry, what am I?

hint: it is not "damp" or anything like that

Alex, Bob and Charlie

"The three of us made some bets.

First, Alex won from Bob as much Alex had originally next Bob won from Charlie as much as Bob then had left finally Charlie won from Alex as much as Charlie then had left. We ended up having equal amounts of money, I began with $ 0"

Which one of the three Alex, Bob, or Charlie is the speaker ?

Cunning Sage

The three wisest sages in the land were brought before the king to see which of them were worthy to become the king's advisor. After passing many tests of cunning and invention, they were pitted against each other in a final battle of the wits. Led blind-folded into a small room, the sages were seated around a small wooden table as the king described the test for them.

"Upon each of your heads I have placed a hat. Now you are either wearing a blue hat or a white hat. All I will tell you is this- at least one of you is wearing a blue hat. There may be only one blue hat and two white hats, there may be two blue hats and one white hat, or there may be three blue hats. But you may be certain that there are not three white hats."

"I will shortly remove your blind folds, and the test will begin. The first to correctly announce the colour of his hat shall be my advisor. Be warned however, he who guesses wrongly shall be beheaded. If not one of you answers within the hour, you will be sent home and I will seek elsewhere for wisdom."

With that, the king uncovered the sages' eyes and sat in the corner and waited. One sage looked around and saw that his competitors each were wearing blue hats. From the look in their eyes he could see their thoughts were the same as his, "What is the colour of my hat?" For what seemed like hours no one spoke. Finally he stood up and said, "The colour of the hat I am wearing is . . ." (what colour is his hat? explain)


by world_pride

Fatal Attraction !

In the autumn of 1912, the ocean linear Olympic, one of the world's biggest ships at the time, was steaming ahead out in the high seas, when another much smaller ship, the cruiser Hawk, rapidly approached it on a parallel course a hundred meters away.

As soon as the two ships took up a position where one pointed the other, a surprising thing happened. the Hawk sharply veered off its course, as if obeying some invisible force, turned the big liner and heedless of the helm rammed into it.The impact was so great that it made a big gash in the Olympic's hull.

A tribunal examined this queer case and found the Olympic's Skipper guilty, as, according to its ruling, he had failed to issue orders to yield the right of passage to Hawk. Consequently, the tribunal, as you can gather, saw nothing extra ordinary about it at all, attributing the the accident to the skipper's negligence.

Actually this was the result of a totally unforeseen cicumstance, a case of mutual attractions of ships at sea and the answer lies in basic physics.

Why do ships attract one another ?

Murder Mystery

One the morning of July 17 The body of Rick litopale was found on his apartment floor; there were only 3 suspects Julie Litopale, his wife, Felix roberston, a friend, and Lynda litopale, his mom. Here are their allibi's

Julie was trying to remember as she was looking at her shoes to her left, Well I came home from work, as usual, and I found my husbands body on the floor, I check and he wasn't breathing, so I called the Police, he had told me before I left, Felix and his mom was coming over later.

Felix came over after I had called him, he said, Well I had come over and had a few beers and I left

His mom said well I had just come over to see my son after a couple of years when I went to Europe.

Well everyone's allibi seems air-tight, can you help solve the murder?

The train to clarksville

Mr. Moody grumbles about bad time-keeping trains from morning till night!.
On one particular morning he was quiet justified.
His train left on time for the one hour journey, to Clarksville, and it arrived 5 minutes late.
However, Mr. Moody 's watch showed it to be 3 minutes early, so he adjusted his watch by putting it forward 3 minutes.
His watch kept time during the day, and on the return journey in the evening the train started on time, according to his watch, and arrived on time, according to the station clock.
If the train travelled 25 percent faster on the return journey than it did on the morning journey, was the station clock fast or slow, and by how much?




as always by world pride

an eggy breakfast

Two fathers and two sons sat down to eat eggs for breakfast. They ate exatly three eggs, each person had an egg. how is this possible?







by:world_pride

4 Men

Four men were in a boat on the lake. The boat turns over, and all four men sink to the bottom of the lake, yet not a single man got wet!Why?

a horse race

a wealthy father had 2 sons. each son had 1 horse so when the father died in his will he wrote " all my wealth goes to the son whos horse comes second" . so the brothers started the race but by midday they still hadn't got out of the gate. so a stranger comes by and asks why they are moving so slow so they tell him the story. so the stranger tells them something and they jump on a horse and start racing as fast as they can. what did the stranger tell them?





by:world_pride

Junior Einstein

Further eating the Alphabet Soup, Junior Einstein came up with another cool calculation.

   A B
   C D
   E F
   G H
---------
 I I I

You know which digit among 0-9 is missing here ?

Thats a lot of squares

if you have a 20x20 grid, how many boxes in TOTAL would you get?
thats including all sizes...

A Question

Hey everyone, I'm back. See if you can crack my homemade cipher.

Thew os hti rqaesi uf nhortiit? O khont yua nec rogafi ot uat.

Matthew Lauser

Alphabet Soup !

When the junior Einstein saw a series of G along with the following alphabets in his soup.

   A B C D E
           F
 -----------
 G G G G G G

His mind created an amazing calculation. If you would have known the
operation, you might have known the numbers which each alphabet
represent. Don't you ?