Brain teaser thread

[tom3]

dopcombo, he was in a world where he thought he was the only one left on the planet.. losing all hopes, he jumped off to kill himself... on the way down he heard the phone ring, which indicates that there are more "survivors" besides him..

I just checked my link.. i should work...

 

[Mithras]

Just a question. If you think about it, 97% caffeine free coffee would be 3% caffeine. (meaning, I believe, that after 33.3 cups, you have consumed the equivelant of one FULL cup of caffeine, or enough to probably kill you) At least I think that is the way it works out.

 

[bolomite]

Try this (if I can remember it correctly): You have a piece of rope, which you know for a fact that it takes one hour to burn up (assume a uniform and constant rate of burning). How can you determine when exactly thirty minutes have elapsed? Of course, you may not use any sort of ruler or measuring device.

Hint: Something you might find in an ordinary kitchen could be of assistance.

 

[thEnEuRoMancER]

tom3, regarding your geometry problem

Let's mark the points of the square and the intersecting points of arcs like this:

edit:

square:

DC
AB

intersections of arcs

G
H F
E

Triangles ABG and AFD are obviously equilateral. Angle GAB = 60deg, angle DAF = 60deg, angle DAB = 90 deg, so angle GAF = 30deg. Triangle GAF is an isosceles triangle with two legs GA = 10 and base GF = 2*10*sin(30/2)=20*sin15.

The shaded area consists of a square with side GF = 20*sin15 and of four circle portions with area:

area of portion = area (circle sector AFG) - area (isosceles triangle AFG)
= pi*10^2*30/360 - (10^2*sin30)/2 = 100*pi/12 - 25

The total shaded area is:

area = (20*sin15)^2 + 4 * (100*pi/12 - 25)

 

[Shalmanese]

Okay, A whole bunch of them, hope you dont mind.

will add the answers soon

1. The maker doesn't want it; the buyer doesn't use it; and the user doesn't see it. What is it?

2. What is one word in the English language almost all people pronounce wrong?

3. Before Mount Everest was discovered, what was the highest mountain on Earth?

4. How far can a dog run into the woods?

5. Captain Frank and some of the boys were exchanging old war stories. Art Bragg offered one about how his grandfather led a battalion against a German division during World War I. Through brilliant manoeuvres, he defeated them and captured valuable territory. After the battle he was presented with a sword bearing the inscription "To Captain Bragg for Bravery, Daring and Leadership. World War I. From the Men of Battalion 8." Captain Frank looked at Art and said, "You really don't expect anyone to believe that yarn, do you?" What's wrong with the story?

6. What is one thing that all wise men, regardless of their religion or politics, agree is between heaven and earth?

7. In what year did Christmas and New Year's fall in the same year?

8. A ship is at anchor. Over the side hangs a rope ladder with rungs 30 cm apart. The tide rises at a rate of 1 metre per hour. At the end of three hours, how much of the rope ladder will remain above water, assuming that 6 metres were above the water when the tide began to rise?

9. Why are 1990 American dollar bills worth more than 1989 American dollar bills?

10. How many times can you subtract the number 5 from 25?

11. How could you rearrange the letters in the words "new door" to make one word? Note: There is only one correct answer.

12. Even if they are starving, natives living in the Arctic will never eat a penguin's egg. Why not?

13. Which is correct to say, "The yolk of the egg are white" or "The yolk of the egg is white"?

14. What is at the beginning of eternity, the end of time, the beginning of every end, and the end of every place?

15. There were an electrician and a plumber waiting in line for admission to the International Home Show," One of them was the father of the other's son. How could this be possible?

16. After the new Canon Law that took effect on November 27, 1983, would a Roman Catholic man be allowed to marry his widow's sister?

17. How many animals of each sex did Moses take on the Ark?

18. A clerk in the butcher shop is 5' 10" tall. What does he weigh?

19. A farmer has 17 sheep and all but 9 die. How many are left?

20. How much dirt is in a hole that is 3 ft deep, and 6 inches in diameter?

21. In 1990, a person is 15 years old. In 1995 that same person is 10 years old. How is this possible?

22. What is the surface area of a cube whose one face measures 3 by 5 cm?

23. If I walk into a room with a match and there is a stove, a heater and a kerosene lamp in the room which one do we light first?

24. What 5 letter word can you add two letters to make shorter?

have fun

 

[FirmPete]

bolomite: Fold it in two, cut it.

 

[DaveJ]

Shalmanese:

1. A coffin
2. wrong
3. Mt. Everest
4. Halfway.
5. How would they have known there would be a SECOND World War?
6. The sky
7. 1 AD

Dave

 

[DaveJ]

8. 6 metres.
9. $1990 is worth $1 more than $1989
10. Once.
11. Dunno...
12. Penguins don't lay eggs?
13. Neither. The yolk of an egg is yellow.
14. The letter e.
15. dunno...
16. No, he'd be dead.
17. None. Moses wasn't on the Ark.
18. Meat.
19. Nine.
20. None, it's a hole.
21. The years 1990 and 1995 are BC, not AD.
22. dunno...
23. The match.
24. Short

Dave

 

[tom3]

thEnEuRoMancER, although your method was different than mine.. you got the right answer.. good job!!!



Shalmanese,
1. coffin/casket? as previously answered..
2. Wrong
3. Mount Everest
4. ?
5. ?
6. ?
7. every year
8. 6 meters
9. because 1990 > 1989, just like 5 dollar bills is > than 2 dollar bills
10. infinitely many.. you just start going negative..
11. ?
12. ?
13. both are wrong
14. E
15. one is a woman and they are married
16. ?
17. ?
18. he weighs meat
19. 9
20. none
21. ?
22. that's not a cube..
23. ?
24. short

gotta run for class..

 

[tom3]

ahhh! didnt read the Ark question carefully enough.. =)

 

[allan120]

15. The person who is not the father of the son is the mother of the son.

Here's one...

What's greater than God,
More evil than the devil,
Rich people need it,
Poor people have it,
and if you eat it, you'll die.

[edit]
Heh, answered in one minute by Dave.
[/edit]

 

[DaveJ]

allan120: Nothing.

Dave

 

[allan120]

Answer to #11:

Just rearrange the letters to form "one word".

 

[zbalat]

An easy one.

What has

Forests but no trees

Streets but no cars

Lakes but no water

Cities but no people

 

[DaveJ]

zbalat: A map.

Dave

 

[TheDennis]

1.coffin
2.wrong
3.Mt. Everest (just because it wasn't discovered doesn't mean it isn't still the highest)
4.half way (the other half he is running out of the woods)
5.?
6.the sky
7.every year
8.6 meters
9.$1990 is one dollar more than $1989
10.once (once you subtract 5 from 25 it's no longer 25)
11.one word
12.penguins only mate once a year and only lay one egg (assuming penguins lay eggs)
13.neither the yolk isn't white it's yellow
14.the letter e
15.the electrician and plumber are husband and wife
16.no he's dead
17.Moses didn't take animals on the Ark Noah did
18.meat
19.9
20.there is no dirt in a hole
21.?
22.?
23.the room you walked in all items are in the same room
24.short

 

[imhotepmp]

How about this one:

Marquis did not have a wristwatch, but he did have an accurate clock.
However, he sometimes forgot to wind his clock. Once when this
happened, Marquis went to his sister's house, spent the evening with
her, went back home and set his clock. How could he do this without
knowing beforhand the length of the trip?



imhotep(MP)

 

[Viper GTS]

The one everyone seems to be ignoring:

#5 - It wan't called WWI then.

Viper GTS

 

[DRGrim]

Penguins do indeed lay eggs.

Penguins live only in the Antarctic.

 

[thEnEuRoMancER]

Allan120:

this one is mathematical...how many people need to be in a group in order for there to be a 50% chance that two people in the group share a birthday?

The probability of two people having birthday on the same day p(A) is one minus probability no two persons have the birthday on the same day p(B). p(A) = 1 - p(B)

In a group of n people, there are 365^n possibilities of different birthday combinations. To calculate p(B), we are interested in the number of combinations where no two people have birthday on the same day: 365 * 364 * 363 * ... * 365 - n + 1

p(B) is therefore (365 * 364 * 363 * ... * 365 - n + 1)/365^n < 0.5

The equation is hard to solve analitically but easy to solve in Excel, and the answer is 23.

 

[Jumby]

Ummm what about my birthday.....
It lies on FEB 29! ! ! !
Makes your total to be 366 days in a year

 

[bigbootydaddy]

as in 365! factorial?

 

[azazyel]

1. Do they have a 4th of July in England?
2. How many birthdays does the average man have?
3. Some months have 31 days; how many have 28?
4. How many outs are there in an inning?
5. Is it legal for a man in California to marry his widow's sister?
6. If there are 3 apples and you take away 2, how many do you have?
7. A doctor gives you three pills telling you to take one every half hour. How many minutes would the pills last?
8. How many two cent stamps are there in a dozen?
9. How many animals of each sex did Moses take on the ark?
10. A farmer has 17 sheep, and all but 9 die. How many are left?

These are really easy but still fun.

 

[prodigy]

1. Do they have a 4th of July in England?

Yes

3. Some months have 31 days; how many have 28?

all of them

4. How many outs are there in an inning?

6

5. Is it legal for a man in California to marry his widow's sister?

If the sister is into necrophelia

6. If there are 3 apples and you take away 2, how many do you have?

2

7. A doctor gives you three pills telling you to take one every half hour. How many minutes would the pills last?

1 hour

8. How many two cent stamps are there in a dozen?

12

9. How many animals of each sex did Moses take on the ark?

Moses didnt go on the ark

10. A farmer has 17 sheep, and all but 9 die. How many are left?

9

 

[azazyel]

Right on!