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General => The Shed => Topic started by: Jesse on June 10, 2004, 20:31:49

Title: Get those brain cells working!
Post by: Jesse on June 10, 2004, 20:31:49
Sorry this is nothing to do with gardening but it is something my 11 year old nephew had me puzzled over and I still don't believe there's an answer to it, a mathamatical anomalie I think  :-[  Maybe someone can provide an answer.

Three ladies buy a lamp worth £30.
They decide to split the cost evenly between them so they pay £10 each.
After the ladies leave the shop the shopkeeper realises that he has overcharged them and the cost should have been £26.
He gives his assistant 4 £1 coins and tells him to catch up with the ladies and give them the money.
The assistant decides that he will give each lady £1 and keep the 4th £1 coin to make things easy (i.e. each lady gets £1 back and there is no need to try to split the last £1 coin).

How much did each lady pay for the lamp?

Well my working is that they each paid £10 but then got £1 back, that makes £9 each. Yes?

Well then take £9 x 3 ladies, that's = £27, right?

Take £27 and add the £1 that the shop assistant kept (honest man!), that = £28, right?

Well what happened to the other £2 then?  ??? ???
Title: Re:Get those brain cells working!
Post by: Gardengirl on June 10, 2004, 21:55:17
Hi Jesseveve,

Hub and I have worked this out for you - quite simple really:

£9 x 3 ladies = £27 paid
£26 is in shop keeper's till (after taking out £4 overpaid)
£1 in assistant's pocket

You can't add the £1 to the £27 as they will then have paid £28 which isn't the case.

Hope this is clear :D
Title: Re:Get those brain cells working!
Post by: Palustris on June 10, 2004, 22:09:08
In fact what you have to do is to take away the stolen £1 from the £27 to get back to the £26 which the shopkeeper has in his till. The original £30 is irrelevant.
Title: Re:Get those brain cells working!
Post by: Jesse on June 10, 2004, 22:15:33
Okay, I think I got the last bit wrong, obviously my brain cells aren't working tonight!

We do want to get back to the £30.

£9 each = £27
Plus £1 each (that was given back) = £27 + £3 = £30
Plus the £1 the assistant still has = £31

So there's an extra £1.
Title: Re:Get those brain cells working!
Post by: Mrs Ava on June 10, 2004, 22:32:34
clear as mud!  Now I know why I failed my maths o' level 3 times!  :o
Title: Re:Get those brain cells working!
Post by: Jesse on June 11, 2004, 06:39:48
Okay Mega, I get it!  :D :D

Each lady thinks she's paid £9 but in reality they have only paid £8.6666666666..... that = £25.999999999, call it £26 which is the amount the shop keeper has.

The £1 that the assistant has stolen is subsidised by each lady - £0.3333333 x 3 = £1

So each lady has parted with £8.66666.....(for the lamp) + £0.333333.....(to the thief) = £9

£9 x 3 = £27
Plus the £1 each that they received back = £27 + £3 = £30
No need to add the £1 from the thief as it is already accounted for in the £9

Yes, about as clear as mud!! ;D

I think Gardengirl and Palustris already answered this but I couldn't see the wood for the trees! Can't believe this has puzzled me all day when the answer seems so easy. Thanks to all. :)