Maths Question.

[Pommie]

OK, this may (and probably should) get moved to **** chat but I still think it's maths

Three men go into a restaurant and order a meal. When it comes time to pay the £300 bill, they each give the waiter £100. When the waiter gets to the cashier, he is informed that there has been a mistake and the bill is only £250. Being a little crafty, the waiter pockets £20 and gives the 3 men £10 each back.

So, the 3 men have each payed £90 for their meal and the waiter has £20 in his pocket. 3*90 = 270 + 20 = 290. Where is the other £10?

Mike.
Woops, just noticed the sub heading of this forum "Discuss the complex nature of mathmatics and physics relating to electronic circuitry." Sorry.

 

[Pommie]

I guess a moderator moved this from the Math and Physics forum.

Mike.

 

[Nigel Goodwin]

I guess a moderator moved this from the Math and Physics forum.

Mike.

Yep!, one did!

 

[Pommie]

LOL, maybe I should have started "3 electrons walk into a "

Mike.

 

[eblc1388]

Three men paid $270 for a $250 meal, with the extra $20 in the waiter's pocket.

Now try this:

Can a 10cm sided rigid metal cube pass through a 9.9cm square hole on a stone wall completely to the other side?

Edited: no trick, the metal cube is not suppose to enlarge the hole on the wall. The hole size remains 9.9cm square afterward.

 

[JimB]

Can a 10cm sided rigid metal cube pass through a 9.9cm square hole on a stone wall completely to the other side?

Edited: no trick, the metal cube is not suppose to enlarge the hole on the wall. The hole size remains 9.9cm square afterward.

Probably can on a very cold day when the metal cube contracts due to the cold.

JimB

 

[eblc1388]

Probably can on a very cold day when the metal cube contracts due to the cold.

JimB

On a very cold day, the cube is still 10cm per side and the square hole on the wall is still 9.9cm as the question does not specify any temperature.

Trust me, it will go through. A 10cm diameter sphere can't go through a 9.9cm diameter hole but a cube can go through a square hole with side less than itself. Even I find it hard to believe.

 

[Phasor]

Trust me, it will go through. A 10cm diameter sphere can't go through a 9.9cm diameter hole but a cube can go through a square hole with side less than itself. Even I find it hard to believe.

Yes, you need to turn the cube diagonally.

This is the same reason why sewer pit lids are round, not square; that way, they cannot be dropped down the sewer hole accidentally.

 

[Pommie]

Another old one.

How many "F"'s in this passage.

FINISHED FILES ARE THE RE-
SULT OF YEARS OF SCIENTIF-
IC STUDY COMBINED WITH
THE EXPERIENCE OF YEARS.

 

[_nox_]

3 F's ? ............

 

[Pommie]

Nope, not 3, try again.

 

[Nigel Goodwin]

How about six - takes some noticing though!.

 

[Pommie]

Six it is. It's amazing how many people insist that there are only 3 and are absolutely shocked when you point out that there is one just 6 letters from the end.

Mike.

 

[akg]

6...most of the left brained people leave the F in OF

 

[jodygep]

i found 4 where are the other 2

 

[jodygep]

never mind i found them, right it does take a moment or two! why is that?

 

[Nigel Goodwin]

Just for anyone who's still struggling:

FINISHED FILES ARE THE RE-
SULT OF YEARS OF SCIENTIF-
IC STUDY COMBINED WITH
THE EXPERIENCE OF YEARS.

 

[JimB]

On a very cold day, the cube is still 10cm per side and the square hole on the wall is still 9.9cm as the question does not specify any temperature.

Trust me, it will go through. A 10cm diameter sphere can't go through a 9.9cm diameter hole but a cube can go through a square hole with side less than itself. Even I find it hard to believe.

OK, can you explain how the cube can go through the hole when the sphere cannot?

JimB

 

[eblc1388]

For a cube, you can turn the cube while you try to push it pass the hole. It is true that if one does not turn the cube while pushing it through, it will not pass through.

For a sphere, the dimension at the interface between sphere and hole is always the same, even with turning so it will never go through.

Edited: The vertex of the cube go in first. then some turning...

 

[JimB]

For a cube, you can turn the cube while you try to push it pass the hole. It is true that if one does not turn the cube while pushing it through, it will not pass through.

For a sphere, the dimension at the interface between sphere and hole is always the same, even with turning so it will never go through.

Edited: The vertex of the cube go in first. then some turning...

Am I being particularly thick here?
Can anyone else understand this explanation?
The smallest dimension of a cube is the length of one side, any other line drawn through the cube will be longer, and so will not pass through the smaller square.

Could it be that the original problem has been incorrectly stated?
Could it be that the problem should be how to pass the larger cube through the smaller cube? I believe this problem is known as "Prince Ruperts' Puzzle"

JimB