Math riddles :D

[Seys*]

Hey guys!
So last week i made a bet with a buddy of mine, we are supposed to get a math riddle to each other and first one to solve the other wins! (its nerdish i know )

So it came to my mind to ask the community for riddles and paradox, and lets make a game of it here in the forums!
Any riddle or paradox is welcome!
Cheers

[Deleted]

My brain hurts just thinking about the riddles we got in school.

[Floross]

Aye , this one is a bit old but :

A rope ladder hangs off a boat and the current water level covers 4 out of the 20 steps of the ladder. The space between each step of the ladder is 20 cm. If the water level rose by 12 cm per hour in how many hours would the water reach the 7th step of the ladder ?

[Leeuwke]

Aye , this one is a bit old but :

A rope ladder hangs off a boat and the current water level covers 4 out of the 20 steps of the ladder. The space between each step of the ladder is 20 cm. If the water level rose by 12 cm per hour in how many hours would the water reach the 7th step of the ladder ?

Assuming the boat is effectively floating on the water, the 7th step of the ladder would never get reached by the water.

[Floross]

True but you coulda gave people a few hours to bash their heads for the fun of it amirite ?

[arons4]

Aye , this one is a bit old but :

A rope ladder hangs off a boat and the current water level covers 4 out of the 20 steps of the ladder. The space between each step of the ladder is 20 cm. If the water level rose by 12 cm per hour in how many hours would the water reach the 7th step of the ladder ?

5 Hours
moar letters

[Cowt]

So last week i made a bet with a buddy of mine, we are supposed to get a math riddle to each other and first one to solve the other wins!

Couldn't getting help from others be considered cheating?

[Deleted]

Theres a fifth of a cake, a sixth of a cake and a seventh of a cake on a plate! Now we have Satoko here who can eat an entire cake in 60 seconds. If she ate every piece, how much of the cake would remain on the plate?

Higurashi no Naku Koro ni Kai ftw :3

[Deleted]

Here you go,

My math teacher showed this at class(I was incredibly close)



Ohea yhea,I forgot

You must tell why/from where is that square in the middle of the triangle (the triangles piaces are NOT changed in size or whatever,they are the same)

Its not an illusion or anything that kind,pure mathematics

[Hetrofi]

Here you go,

My math teacher showed this at class(I was incredibly close)



Ohea yhea,I forgot

You must tell why/from where is that square in the middle of the triangle (the triangles piaces are NOT changed in size or whatever,they are the same)

Its not an illusion or anything that kind,pure mathematics

theres just one big triangle =)


you are going to hotel with 2 friends.
You read online that it costs 3000 gold for all 3 to set your hearthstones there.
You go the the inn, and pay 3000 together.
When you get outside, you see that theres a factiondiscount and that its only 2500 gold for 3 persons.
You go inside and complain.
The innkeeper decides to give you all back 100g, so essentially you all paid 900g, while he himself keeps 200g.

So, you 3 paid 900 each, for a total of 2700 and the innkeeper got 200. Wheres the missing 100 gold? Blizzard nerf? Ah cuts?

[Deathsenemy]

Theres a fifth of a cake, a sixth of a cake and a seventh of a cake on a plate! Now we have Satoko here who can eat an entire cake in 60 seconds. If she ate every piece, how much of the cake would remain on the plate?

Higurashi no Naku Koro ni Kai ftw :3

If they ate it all, then none is left.

---------- Post added 2011-05-29 at 02:56 PM ----------

theres just one big triangle =)


you are going to hotel with 2 friends.
You read online that it costs 3000 gold for all 3 to set your hearthstones there.
You go the the inn, and pay 3000 together.
When you get outside, you see that theres a factiondiscount and that its only 2500 gold for 3 persons.
You go inside and complain.
The innkeeper decides to give you all back 100g, so essentially you all paid 900g, while he himself keeps 200g.

So, you 3 paid 900 each, for a total of 2700 and the innkeeper got 200. Wheres the missing 100 gold? Blizzard nerf? Ah cuts?

Complete the accounting with $2700 (hotel AND inkeeper) with 300g(change from $3000) = $3000(money originally paid by the people)

Look at it as a fraction. Pretty simple. Typing on iPhone or I would give better explanation.

[Spl4sh3r]

you are going to hotel with 2 friends.
You read online that it costs 3000 gold for all 3 to set your hearthstones there.
You go the the inn, and pay 3000 together.
When you get outside, you see that theres a factiondiscount and that its only 2500 gold for 3 persons.
You go inside and complain.
The innkeeper decides to give you all back 100g, so essentially you all paid 900g, while he himself keeps 200g.

So, you 3 paid 900 each, for a total of 2700 and the innkeeper got 200. Wheres the missing 100 gold? Blizzard nerf? Ah cuts?

There isn't anything missing, they gave 3000, they got 300 back which ends at 2700 of which 200 the innkeeper keeps above the ordinary price of 2500 :P

[Seys*]

Couldn't getting help from others be considered cheating?

dont worry already got mine, just for the purpose of fun!

[Aliessil]

Here you go,

My math teacher showed this at class(I was incredibly close)


Ohea yhea,I forgot

You must tell why/from where is that square in the middle of the triangle (the triangles piaces are NOT changed in size or whatever,they are the same)

Its not an illusion or anything that kind,pure mathematics

That one's easy enough. Although the triangles are the same size, the area covered by the yellow and blue pieces is different. In the first it's 3x5=15, in the second it's 2x8=16 (one square short).

The triangles themselves are irrelevant; they're just defining the quadrangle you have to fit the blue and yellow pieces in to.

[Liara]

2 coins add up to 30 cents, and one of them is not a nickel. What are they?

Also, prove mathematically that "women = problems" (nothing sexist intended, it's just how this little thing works. Could be used with men as well).

[Mmpie]

2 coins add up to 30 cents, and one of them is not a nickel. What are they?

Haha oh man, that is old school A quarter and a nickel (one of them is not a nickel, the other is).

[Liara]

Haha oh man, that is old school A quarter and a nickel (one of them is not a nickel, the other is).

Nah - a penny and a 1972 dime with a Roosevelt imperfection, today worth exactly 29 cents.

[Deleted]

That one's easy enough. Although the triangles are the same size, the area covered by the yellow and blue pieces is different. In the first it's 3x5=15, in the second it's 2x8=16 (one square short).

The triangles themselves are irrelevant; they're just defining the quadrangle you have to fit the blue and yellow pieces in to.

Nope, its the fact that the gradients on the two triangles is different, on the top triangle, both the smaller triangles go inwards. On the bottom one, they go outwards. All of the individual shapes are exactly the same in both big triangles.

[klaps_05]

Give him this math problem:

"P versus NP: The question is whether, for all problems for which a computer can verify a given solution quickly in polynomial time, it can also find that solution quickly. The former describes the class of problems termed NP, whilst the latter describes P. The question is whether or not all problems in NP are also in P."

Good luck!

[Deleted]

Give him this math problem:

"P versus NP: The question is whether, for all problems for which a computer can verify a given solution quickly in polynomial time, it can also find that solution quickly. The former describes the class of problems termed NP, whilst the latter describes P. The question is whether or not all problems in NP are also in P."

Good luck!

Yeh, giving him a problem that the greatest mathematicians ever have failed to prove or disprove would make his job a bit tougher.