[DoctorBeaver (OP)]

I know this is an old chestnut that has been regurgitated in classrooms & bars across the world ad nauseam, possibly causing punch-ups & maybe even the odd revolution in banana republics, but here it is once more just on the offchance someone has been living in a cave all their life.

3 men go to buy a television. They find 1 for £30 and pay £10 each (they must have gone to Cash Converters! []). When they've left the shop, the assistant realises the television was on offer & he should have only charged them £25. He runs after them (obviously NOT Cash Converters!) but instead of giving them back the £5 he gives them each £1 & pockets the other £2 himself.
So, having initially paid £10 each, when the 3 men get £1 each back, they have paid £9 each & the shop assistant has £2.
3x9=27+2=29. Where is the other £1?

I remember sitting in maths (yes, Americans... it's MATHS - PLURAL!)class at school, scribing away on my slate tablet, & puzzling over this. When I asked my teacher to explain it he soundly thrashed me (for which I am, of course, eternally grateful) & told me not to be insolent.
Since then I have asked numerous people & not yet had a satisfactory answer. Can any of the whizzo maths bods here explain it for me? I would hate to meet my maker not knowing the answer.

Thank you [)]

(I've just had a vision of George Dubya - "Hell, I don't know the answer. Didn't the Ay-rabs invent arithmetickle? Well, let's invade Eye-rack")

[ukmicky]

arrrrrrrrrrrrrrrrrhhhhhhhhhhhhhhhhhhhhhh bastard[][]

Michael                                      

[neilep]

I know, I know !!! While each of the men has indeed paid a net £9  this is balanced by the £2 in the assistants pocket and the 25 back at the store.

The final calculation, adding the 27 and the 2 is where the "paradox" arises - the 2 should be subtracted, since the total spent was 27, 25 for the TV and 2 for the delivery of the refund..........errr...does that make sense ?

Men are the same as women.... just inside out !!

[ukmicky]

No[]

Michael                                      

[neilep]

Excellent, glad I could help !!...  :-)

Men are the same as women.... just inside out !!

[DoctorBeaver (OP)]

Neil - that's all very well but it doesn't explain the paradox. The bottom line is that they have paid £9 each & the shop assistant has £2. If you subtract the £2 from the £27 you've only got £25 which means that £5 is missing!

quote: the 2 should be subtracted, since the total spent was 27, 25 for the TV and 2 for the delivery of the refund

That means £3 is missing

[xx(]

[neilep]

Look at it this way Eth.

In the shop till is £30, the assistant takes £5 to refund. Leaving £25 in the till...ok ?...He gives £3 back and pockets £2...

£2 in pocket plus £3 refund plus £25 in shop till = £30....The £27 that they have paid is comprised of the £25 in the till and the £2 in the pocket of the assistant.......YAYYYYY !!

Men are the same as women.... just inside out !!

[Solvay_1927]

Very clearly explained, Neil - top marks again!

Doc - in case you still don't get it, try thinking of it this way: the £30 is really a bit of a red herring.  Imagine if the story went like this:

"3 men go to buy a television. They find 1 for £27 and pay £9 each.  When they've left the shop, the assistant realises the television was on offer & he should have only charged them £25. He pockets the other £2 himself."

Now it's clear that the calculation "3x9=27+2=29" is meaningless. Whereas the calculation "3x9=27-2=25" does mean something - it's the amount of money in the till.

QED


"Do infants enjoy infancy as much as adults enjoy adultery?"

[DoctorBeaver (OP)]

But what about V.A.T.?

[Solvay_1927]

I understand your problem now. It's not a mathematician you need, it's a tax accountant.[]

(And they really CAN work magic with numbers.)

"Do infants enjoy infancy as much as adults enjoy adultery?"