The worlds first riddle!

Ratio of boys to girls in China will still be 1 to 1 or thereabouts.

Births in China.
Well done Adrian, and the others who sent a message with the right answer. I thought I might have had a chance with that.

The ratio is 50-50.

Intuitively, it may feel that the families are adopting a strategy favouring producing a son, but this is incorrect. The families expected number of sons is one, by the definition of the strategy. But the expected number of daughters doesn't drop. Consider:

There is a 1-in-2 chance that the son is the first born, and so no daughters are born.
There is a 1-in-4 chance that the son is the second born, and so one daughter is born.
There is a 1-in-8 chance that the son is the third born, and so two daughters are born.
And so...

Therefore the expected number of daughters is (.50 0 daughters) + (.25 1 daughter) + (.125 * 2 daughters)... = 0.5 daughters.

Lacomus wrote, "The correct road was the middle road.
I said 'the right road'.

Answer: "So, the probability the pixie lied is 68.947%, and you should go right." Cheer up, the right road was the middle road.


This is the very hardest riddle ever.

The Simpson family have some Christmas present trouble. The trouble is not buying them in time - they did that well before the time was up. The problem is that the sticky labels they put on the presents to show who was to receive them, and from whom they were, have fallen off. I guess they were old.

Anyway, a trait that runs in this family is that they have rather bad memories... bad enough; that they are not even certain which presents they bought.

The family consists of Alice, her husband Bruno, their older child Deirdre and her younger brother Chester. Each person gave one gift to each of the other members of the family.

Their memories are not uniformly bad. In fact, one of them is always correct, and another is correct three quarters of the time. The third is right half of the time and the last one is right one quarter of the time.

I'm not going to tell you which is which, though. That would make this riddle too easy.

The following are pieces of discussions among the family, after they opened the presents and tried to figure out their ownership status:

Alice: "Well, this is a mess. I'm pretty sure the water colours belong to Chester, though."

Deirdre: "The DVD player is mine."

Bruno: "I thought the DVD player belonged to Alice."

Deirdre: "The textbook on differential equations, and the silk ribbon both belong to mom."

Bruno: "No, the textbook is Chester's."

Chester: "And the pocket watch is yours, right?"

Bruno: "The diary and the box of chocolates are mine."

Chester: "And the silk ribbon, too."

Bruno: "I gave the model train."

Chester: "And the DVD player came from me."

Alice: "I do believe the ribbon is mine."

Deirdre: "The loudspeakers are yours, though, dad."

Bruno: "I got the mittens from Alice."

Chester: "I'm the one who gave the silk ribbon."

Alice: "The model train was given by Deirdre..."

Deirdre: "The socks belong to mom."

Alice: "I gave the diary."

Deirdre: "And the pocket watch is Chester's."

Alice: "The diary and the pocket watch belong to Deirdre."

Chester: "The diary is from me."

Bruno: "I gave the DVD player, didn't I? I think so."

Chester: "I gave the textbook."

Alice: "I think the loudspeakers were a gift to Bruno from Chester."

Deirdre: "The model train is dad's."

Chester: "And mom gave the pocket watch."

Deirdre: "The chocolates are Chester's."

Bruno: "I seem to recall Alice was the one who gave the box of chocolates."

Bruno: "Hmm. I gave the socks, I do know that."

Alice: "The textbook came from Bruno."

Deirdre: "I gave the water colours to Chester."

Chester: "And in return, I gave you the pocket knife."

Alice: "I don't think you gave the pocket knife."

So, can you figure out what belongs to whom
On the other hand, more specifically, who gave the pocket knife,
and to whom




Riddle (Parts 1 & 2)

If you fear that I am near,
Here's a wise word in your ear,
You may look forth and aft for me,
But to do so simultaneously,
Ensures you'll just look straight through me,
Even if I'm right behind thee.

I am not a friend of man,
I'll try to kill you if I can,
I am a lover of the night,
But I warn you don't try to cross me,
I tell you now that that would cost me.

What am I

funny!

Do not put your faith in such trinkets of deceit.

That Simpson family one is BLOODY hard. I'm only about half way through and already onto my second page of scribbles. Will be back.

Adrian, don't bet on it. If you get the right answer, to you goes the crown.

In the meantime a little something for the maths crowd.

Recently you invited your friend Sally- a mathematician by vocation and gambler by vice - to a dinner party with some married couples. You knew the couples only a little, and you were quite sure Sally knew them not at all. In a demonstration of the subtleties of probability, she offered a series of three wagers.

She turned to the couple immediately to her left and inquired how many children they had. "Two," they replied.

"And is the oldest a girl?" she asked.

"Yes."

Turning to you she offered, "I'll wager even money that the other child is a boy."

Next, Sally turned to the couple on her right and asked the same question about their progeny. Again, "two" was the answer.

"And, of your children, is one of them a girl?" she asked.

"Yes."

Turning to you she said, "I'll wager even money that the other child is a boy."

"Finally, I'll let you know that I have exactly one sibling, and that sibling is younger than I. Will you wager even money that the sibling is a boy?"

Sally was trying to prove a point about the subtleties of probability - she knew nothing about the children of the couples present. What were your odds of collecting on each of three wagers?

Despite first appearances, none of Sally's three wagers has the same odds. What are they

PS. "Do not put your faith in such trinkets of deceit."
You may be onto something there.

Try

I reckon the answer to your word-puzzle is a vampire.

The Simpsons I will leave to Adrian's superior abilities; it looks like a lot of work to me.

I'll have a think on those odds if I get a chance during coffee break

Children:

1st case - 1:1 boy: girl
2nd case : 2:3 boy:girl
3rd case: 1:1 boy:girl

Seems to me that 1st and 2nd cases are exactly the same.
I assumed that 50% of children are boys, and that for any child the chance is the same of being a boy.

This goes against all three cases having different odds, but what I don't see I cannot say.

Uhh sorry, second case is 2:1 boy:girl

Riddle (Parts 1, 2 & 3) although, part 3 not required, as Lacomus has the answer - clever.

If you fear that I am near,
Here's a wise word in your ear,
You may look forth and aft for me,
But to do so simultaneously,
Ensures you'll just look straight through me,
Even if I'm right behind thee.

I am not a friend of man,
I'll try to kill you if I can,
I am a lover of the night,
But I warn you don't try to cross me,
I tell you now that that would cost me.

I need you more than you need me,
Even though I may murder thee,
The essence of yourselves I seize
To prolong my own final demise,
But even so I may not mind,
Converting others to my kind.

What am I?

The answer is a Vampire.


I am sorry. Yes, I apologise in advance for posting what appears to be impossible, but is not if you were an apprentice of Einstein.

Snow starts falling at some time before noon on a cold March morning. At noon, a snowplough starts ploughing a highway. At 1 pm, the plough has advanced 2 miles, but it takes another 3 hours to do the next 2 miles. What time did it start to snow



When people do not want me,
I take what they need.
When people wanted me,
I took what they did not need.
However, civilised people do not want me these days.

What am I

Relative, I missed your post by a minute, or so. This is my answer to your reply.

Sally's first wager is closest thing to a fair bet she offers. The fact that the older child is a girl has no bearing on the sex of the younger child. Your odds of collecting on this bet are basically fifty-fifty.1

Sally's second wager is less than fair. While the youngest child of any random family is equally likely to be a boy as a girl, Sally has carefully chosen a subset of the population to help her out.

There are four possible combinations of two children families: both boys, both girls, older boy/younger girl, and older girl/younger boy. Her question eliminated the both boys combination. Of the remaining three possibilities, two will give her a win. Unless the couple she has asked has two girls, the bet is in her favour.

If you are unconvinced, consider this: What if the couple had responded "No, neither of our children is a girl?" Sally would have been unable to offer the wager she did (at least reasonably), and would have had to move on to the next couple.

If you took Sally's third wager, you deserved what you got. What are the odds that Sally does not know the sex of her own brother? :wink:

HAHAHAHAHAHAHAHAHAHAH!!!!!!!!!

HIHIHIHIHIHIHIHIHIHIHIHIH

OOOOOOOOOOOHHHOOOOOOOO

BUUUUUUUUUUU

Relative, laughter makes the world go round. [size=7]Two trains start one hundred miles apart and head straight toward each other at ten miles per hour. A bird perched on the front of one-train flies toward the second at twenty miles an hour. The moment it reaches it, it turns around and heads back. It repeats this process until the trains meet. [/size]
How far does the bird fly

The tricky font isn't fooling anyone, Try. :wink: It is still 100miles.

You are far too clever for me. Maybe, it is because you have long coffee breaks.
The only breaks we have are in our bones, from long days of toil. You will need to put on the brakes to answer this.

You have found a floppy disk and are trying to identify the data on it. You open up the tab-delimited file and view the following (shown here in comma-separated format):

0.387,4878,58.65,87.97
0.723,12104,243,224.7
1,12756,1,365.26
1.524,6787,1.026,686.98
5.203,142800,0.4083,4331.984
9.539,120660,0.425,10760.559
19.18,51118,0.7458,30681.84
30.06,49528,0.7958,60194.848
39.53,2300,6.39,90474.902

What should the row and column headings be

I take a small crumb of comfort from the fact, that between sips, you did not look at your watch to see what time the snow started! :wink:

There are two solutions to the 'bird' problem - you can either sum an infinite series of bird's flight from one train to the other, or you can simply determine the time as (distance)/(speed of trains) and multiply (velocity of bird)*(time).

Allegedly John von Neumann was presented with this puzzle, thought for a second, and answered correctly. When asked how did he calculate it, he answered: "Easy, I summed the infinite series."

Try - your puzzle
reminds me of my anagram:

Pearls turn
in vacuum up there;
Just one sun
put Men
under star array.

Relative

Relative

Well well well; not long back you were drawing parallels between my lowly self and Dirac and now you are doing the same between my lowly self and von Neumann. You see, I solved the 'bird' problem by summing the infinite series and did it in my head in very little time.

Now while I am again honored I must politely decline the honor because summing that particular infinite series is not so very difficult, and if I do claim any credit it is merely for spotting how easy it is.

The bird flies 2/3 times 100 to the approaching train. It then flies back
2/3^2 times 100 and then 2/3^3 times 100, etc.
2/3 + 2/9 + 2/27 + 2/81 . . . is simple for the following reason. The original 2/3 can be described as 'the top is one less than the bottom'. If, in order to turn this into ninths we multiply both top and bottom by three it follows that the top will now be three less than the bottom. But we add two ninths so again the top is one less than the bottom. We do the same to convert to twenty-sevenths and get 26/27. We do it again to convert to eighty-firsts and again we have 80/81. So no matter how many place we take it to the top will always be one less than the bottom and this is as close to 'one' as makes no difference. And one times a hundred is one hundred!

As is always the case it took far less time to do it than to explain it.

Try

I would suggest , re. the bird problem, that there never is a 'right' method.

Any method that provides a correct answer and cannot provide a wrong one is as 'right' as any other method.

The floppy disk

These are the planets in the solar system and the rows are ; Distance from the Sun in A.U.; diameter in kilometres; day relative to Earth; year relative to Earth.

The 365.26 is, as you say, very helpful. But a bigger clue are those '1's; only one entry has them and that one has more than one.

The alphabet - easy for a scrabble player :wink:

I've sent a pm concerning the solution to the Simpson presents puzzle.

Lacomus wrote, "I would suggest , re. the bird problem, that there never is a 'right' method. Any method that provides a correct answer and cannot provide a wrong one is as 'right' as any other method."

So very true


New number.

Jane's parents were still unpacking. It was her first day at the new school, and she was almost out the door when her Mom shouted, "Phone home at lunch time. We'll want to know how the morning went."

"But I don't know the new phone number!"

"It's easy," her Mom called, "just remember:

The 1st, 2nd, and 3rd digits are all the same. Together they make a three-digit number that is 70 less than the square of the product of the first two digits.
The 4th digit is the greatest common factor of 28 and 35.
The 5th digit is the cube root of 27.
The 6th digit is the fourth prime number.
Subtract -9 from -6 . The difference is the 7th digit."

What is Jane's new phone number