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solve this puzzle:
In a country in which people only want boys, every family continues to have children until they have a boy. If they have a girl, they have another child. If they have a boy, they stop. What is the proportion of boys to girls in the country? Assume these are infinite families in the country?
From i_online
If we consider, n as the total number of families,
Then the ration of number of boys to girls will always be 2:n, where n is the number of family and n>=1
Thanks
i'm sorry but i'm not very good with math(also with English)
so is his answer were right?
it's seems to be logical .
any way this is a great puzzle, do you have one that not involved with math?
nice puzzle.
Keep sharing.
Multiply of 37 by multiplies of 3:
3 x 37 = 111
6 x 37 = 222
9 x 37 = 333
12 x 37 = 444
15 x 37 = 555
18 x 37 = 666
21 x 37 = 777
24 x 37 = 888
27 x 37 = 999
Nice one:
111.111.111 x 111.111.111 =
12.345.678.987.654.321
Trapeze:
1 x 9 + 2 = 11
12 x 9 + 3 = 111
123 x 9 + 4 = 1111
1234 x 9 + 5 = 11111
12345 x 9 + 6 = 111111
123456 x 9 + 7 = 1111111
1234567 x 9 + 8 = 11111111
12345678 x 9 + 9 = 111111111
another Trapeze:
1x 8 + 1 = 9
12 x 8 + 2 = 98
123 x 8 + 3 = 987
1234 x 8 + 4 = 9876
12345 x 8 + 5 = 98765
123456 x 8 + 6 = 987654
1234567 x 8 + 7 = 9876543
12345678 x 8 + 8 = 98765432
123456789 x 8 + 9 = 987654321
and another one:
0x 9 + 8 = 8
9 x 9 + 7 = 88
98 x 9 + 6 = 888
987 x 9 + 5 = 8888
9876 x 9 + 4 = 88888
98765 x 9 + 3 = 888888
987654 x 9 + 2 = 8888888
9876543 x 9 + 1 = 88888888
98765432 x 9 + 0 = 888888888
987654321 x 9 - 1 = 8888888888
9876543210 x 9 - 2 = 88888888888
Nice puzzle.
Keep going neerajsingh.
This thread made into Sticky. If it is not updated daily it will be removed.
@i_online, in view of making this thread sticky two of your puzzles have been added here and your original posts are moved.
Cheers
indianbaba.
Thanks indianbaba for making this thread sticky. It would surely help others.
Finger Multiplication
by Sidney Kolpas
Mathematics Teacher April 2002
It requires that the students hold both hands up, with palms facing the student. The student counts his or her thumbs and fingers consecutively
from left to right, with the thumb on the left hand representing the number 1 and the thumb on the right hand representing the number 10. To multiply n times 9, where 1 <= n <= 10 and where n is a whole number, the student bends down the nth finger. The number of fingers to the left of the bent finger represents the tens-place digit of the product, whereas the number of fingers to the right of the bent finger represents the ones-place digit of the product.
The figure below illustrates 7 x 9.
http://www.pen.k12.va.us/Div/Winches...les/finger.jpg
Mr. Kolpas explains why this works in his article in the April 2002 issue of the Mathematics Teacher.
Courtesy : http://www.pen.k12.va.us
i never knew that.
That was something marvellous.
Keep sharing.
Finger Multiplication by Nine
by Paul Horrell
Mathematics Teacher February 2003
The "finger folding" multiplication by 9 can be expanded to include multiplicands up to 99.
Code:The algorithm used is similar to the following:
To multiply a two-digit number by 9,
ENTER the multiplicand by forming a V between the tens-digit finger and the next finger to its right (SPREAD).
ENTER the units digit by FOLDing the units-digit finger.
Code:To read the product
Hundreds digit: Count the standing fingers before the SPREAD.
Tens digit: Moving from left to right, count the fingers from the SPREAD to the FOLD; wrap around if necessary.
Units digit: Count the standing fingers to the right of the FOLD.
Code:Example:
48x9
Enter (1 2 3 4 _ 5 6 7 F 9 0)
Read:
Hundreds (1 2 3 4) 4
Tens (5 6 7) 3
Units (9 0) 2
Example with wraparound:
83 x 9
Enter (1 2 F 4 5 6 7 8 _ 9 0)
Read:
Hundreds (1245 6 78) 7
Tens (9 0 1 2) 4
Units (45 6 7890) 7
Climbing Snail
A snail is at the bottom of a 20 meters deep pit. Every day the snail climbs 5 meters upwards, but at night it slides 4 meters back downwards.
The Question: How many days does it take before the snail reaches the top of the pit?
Abracadabra with Apples
http://static.flickr.com/55/148665709_504ccbf4c8.jpg
In Miss Miranda's class are eleven children. Miss Miranda has a bowl with eleven apples. Miss Miranda wants to divide the eleven apples among the children of her class, in such a way that each child in the end has an apple, but one apple still remains in the bowl.
The Question: Can you help Miss Miranda?
Chain Connection
http://static.flickr.com/55/148665709_504ccbf4c8.jpg
You have five pieces of chain, each consisting of three links. You want to make one long chain of these five pieces. Breaking open a link costs 1 euro, and welding an open link costs 3 euros.
The Question: Is it possible to make one long chain of the five pieces, if you have just 15 euros?
$ THE MISSING DOLLAR RIDDLE $
http://static.flickr.com/55/148665709_504ccbf4c8.jpg
Three friends check into a motel for the night and the clerk tells them the bill is $30, payable in advance. So, they each pay the clerk $10 and go to their room. A few minutes later, the clerk realizes he has made an error and overcharged the trio by $5. He asks the bellhop to return $5 to the 3 friends who had just checked in. The bellhop sees this as an opportunity to make $2 as he reasons that the three friends would have a tough time dividing $5 evenly among them; so he decides to tell them that the clerk made a mistake of only $3, giving a dollar back to each of the friends. He pockets the leftover $2 and goes home for the day! Now, each of the three friends gets a dollar back, thus they each paid $9 for the room which is a total of $27 for the night. We know the bellhop pocketed $2 and adding that to the $27, you get $29, not $30 which was originally spent. Where did the other dollar go????
If he has his fridge :shock: with lots of soda and something to eat with him then it will take him 16 Days to reach the top of the pit else he will starve to death :oops:Quote:
Originally Posted by http://neerajsingh.bizhat
Am i right :?:
In jan 1 there was a lotus in a pond.
The number of lotus is doubled every night.And at last one day the pond was full of lotuses on jan 30.
Problem:-
When was the pond halfly filled,i need the date?
Congratulations !!! You Have Cracked It !!!Quote:
Originally Posted by sohaibrazzaq
http://img128.imageshack.us/img128/9750/sexy9gk.gifhttp://img143.imageshack.us/img143/3...m07june8oz.gif
Is it Jan 29?Quote:
Originally Posted by nokia-zone
Pete and Repete
Teller: OK, listen closely, Pete and Repete are in a boat. Pete jumps out. Who is left in the boat.
Victim: Repete!
Teller: Pete and Repete are in a boat. Pete jumps out. Who is left?
Victim: I already told you! Repete!
When the victim says Repete, the answer to the question, the teller repeats the joke till the victim catches on and doesn't say Repete
Intelligence Test
First, draw the diagram pictured below. Do not let your victim see you doing this it will ruin the test
http://static.flickr.com/65/155521785_de63d6c062_m.jpg
Start from the section labeled one but do not point to it for your victim.
Teller: Circle the biggest circle.
The correct answer would be to circle the perimeter of the diagram as that is the biggest circle. The victim may however circle the largest circle in section one but keep in mind this is wrong but make no other comments.
Next move to section 2. Again, do not point to the section for your victim.
Teller: Circle the biggest X.
The right answer would be to circle the X that divides the diagram into four sections. This is the same idea as in section one.
Now move on to section 3.
Teller: This is the purple house. The purple house is one story and every thing in it is purple. The doors are purple, the sofa is purple, the refrigerator is purple (go on as long as you like) now what color are the stairs?
The correct answer is: since the purple house is one story, there are no stairs!
Finally there is section 4
Teller: This is a picture of a tree in a park. It's winter and the wind is blowing to the left. Which way do the leaves go?
The correct answer is they wouldn't go anywhere because it is winter and there are no leaves on the tree.
Scoring
Each section is worth 25 percent. Add up the sections the person got wrong (example, 2 sections would be 50% stupid) and don't forget the appropriate comment.
0% Stupid: You must have cheated
25% Stupid: About average
50% Stupid: Did you miss your morning coffee
75% Stupid: Are you sure you're awake
100% Stupid: Hey, as long as you did your best
Courtesy: http://www.justriddlesandmore.com
Photo currently unavailable?
I have updated it indianbaba. Now we can see the picture.Quote:
Originally Posted by indianbaba
Thanks for pointing it out :-)
that is a hard one... i have no idia...
these are extreme thanks for sharing
Dont post like this. Post something meaningful and relevant to the topic.Quote:
Originally Posted by p-muzic
Your math is excelent, but I have a question. Where do you leave biology? Some countries are more propense to having boys, so I thing you have to add genetics to the equation.
Also yo have to add the war factor. If the country is in war the proportino of girls to boy varies a lot. More girls for that matter.
WOW!!! Nice stuff here "neerajsingh".Quote:
Originally Posted by http://neerajsingh.bizhat
It really got me thinking...
As for the first boy/girl puzzle, there is no answer. Unless you find the average number of girls concieved before the boy, this ratio could be anything. :?
If it was in Dutch, maybe I knew the answer, but my Englisch is not very good, so....
Wow, amazing how people can think so...advanced? Heh.
My english is not good either
pfft nither is mine and i am english
I like these puzzels. Can I post one I have?
Sure. you can post your puzzles.Quote:
Originally Posted by ?lol?yay?
really really fun!
be happy,
Give the last apple to the last child together with the bowl. Correct?? :DQuote:
Originally Posted by http://neerajsingh.bizhat
miss .miranda must be one among the student.....
Lol, that must be correct :DQuote:
Originally Posted by andysoo89
Thanks for cracking it, i was going to get a headache for these puzzles. :lol:
I am happy to join the puzzle discussion forum. Thanks for sharing puzzles.
Do you know the largest number known to mathematicians?. Name that number. Share your knowledge.
1) 1 000 000 000999
2)1 000 000 000 000
3)1 000 000 000 001
4) ?
The proportion is 1:1, because in every birth there's a 50% for each. To convience you:
1/2 of the families have 1 boy.
1/4 have 1 girl + 1 boy.
1/8 have 2 girls + 1 boy.
1/16 have 3 girls + 1 boy.
and so on.
So If N is the number of families, the total number of boys is:
(1/2 + 1/4 + 1/8 + 1/16 ...) N = N
Which is obvious since every familiy has 1 boy.
The total number of girls is:
(1/4 + 2* 1/8 + 3* 1/16 + ) N = N.
A number - 10 raised to 100 - is named as googol. It is written as 1 with 100 zeros.
googol pex is the largest number known and is 10 raised to googol - 1 with googol zeros.
Try this puzzle :
Milling flour charge is 10 % of item milled. What is the amount of flour required so that after deducting 10 % for milling charge, he gets 100 kg ?.