View Full Version : Where's the missing Quid?

forget

5th Apr 2005, 22:10

Maybe I used to know the answer - but………..

Three customers in a restaurant. Bill comes to £30. Waiter takes £10 off each customer and takes the money to cashier. Cashier points out that the bill should be £25 and gives the waiter £5 in coins. Waiter pockets £2 and gives the customers £1 each. Each customer has therefore paid £9, total £27. Waiter has £2. Grand total £29. Where's the missing quid?

Simple explanations please.:ok:

Grainger

5th Apr 2005, 22:16

Customers have paid a total of £27

Restaurant gets £25, waiter gets £2, total £27

There is no "missing quid".

The catch is in the way the £5 excess is divided up. The waiter gives back £3 and pockets £2.

The £3 given back is the difference between £27 and £30. But the problem is worded to make it sound as if the £2 pocketed by the waiter is added to the £27 - when it is of course part of the £27.

Onan the Clumsy

5th Apr 2005, 23:07

Trust a Scotsman to know where it went :p

BlueDiamond

6th Apr 2005, 00:19

You can do a similar thing to amuse a child. Tell the child that most people have ten fingers but you have eleven. Hold up one hand then count backwards raising one finger at a time ...

ten ... nine ... eight ... seven ... six

Then hold up your other hand and say, "And five is eleven."

Doesn't worl well if you are missing any fingers though. :rolleyes:

The Invisible Cat

6th Apr 2005, 00:36

http://www.pprune.org/forums/showthread.php?s=&threadid=168961&highlight=pockets

30th March 2005 : less than a week ago

:rolleyes:

BillHicksRules

6th Apr 2005, 09:04

Dear all,

The reason this works is due to the hierarchy of arithmetic.

You must do multiplication and division before addition or subtraction. If you mix them up you end up with a situation like the one here.

Each person paid nine pounds therefore 9 x 3 = 27

Restaurant needs 25 therefore 2 left over for waiter.

Cheers

BHR

Konkordski

6th Apr 2005, 14:28

The reason this puzzle works is because the mathematical jiggery-pokery generates the figure "£29"...which is close enough to the original "£30" to make it tempting to believe that there's really something funny going on.

This deflects attention from the fact that the "£29" is a completely arbitrary result derived from nonsense mathematics.

If you think about it, there's no mathematical reason why the room payment and the waiter's money should ever add up to the original £30. But people assume that it should, simply because of the way the problem is presented.

(The flaw becomes obvious when you pick different numbers. Imagine the three guests pay £10 each...but the rooms actually cost £5...waiter sent up to return 15 pound coins...but he keeps £3 and gives £12 back...£4 to each guest.

So the guests pay £6 each for their rooms...totalling £18. Waiter has £3. Add the two together = £21. Which is nowhere near the original £30. But it isn't meant to be.)

airship

6th Apr 2005, 14:45

Where's the missing quid? Where's the missing waiter?! - He was supposed to split the tips with the chefs. Funnily enough, the kitchen porters have been muttering about overly-heavy garbage bags recently... :p

IB4138

6th Apr 2005, 21:00

Headline in local paper following morning

" Waiter found dead in steak pie...local men saught. Dough is possible motive"