stupid maths riddle, wrecking my head!

sd123

3 men go into a bar and order a round of drinks, it comes to 30 euro. each man pays 10 euro. after a while, the barman realises he made a mistake, the drinks should've costed 25 euro. he comes down with the extra 5 euro to refund them. the men decide that it was too awkward to split up 5 euro between 3 people and each decides to take 1 euro and gives the extra 2 euro to the barman as a tip. now each man paid 9 euro and the barman gets 2 euro. that makes 3(9) + 2 = 29 euro, wheres the extra 1 euro gone?????

someone gave this smart arse explanation:

the next night, two of the lads buy a round of drinks, again it comes to E30. each man pays E15. again the barman realises he overcharged them by E5. he comes down with the refund. Again each man gets E1 and gives the barman a E3 tip. now, each man paid E14 and the barman gets E3. this makes up E31. THATS THE EXTRA E1.:D

can anyone explain this to me:o

stipey

Each man hasn't paid €9 for the drink...

3 drinks = €25 (at the proper price)
Now each man takes €1 back having been overcharged.
This makes €25 for the 3 drinks
€3 that they took in change. (i.e. given back to them when the barman realised his error)
€2 that they gave to the barman as a tip.

add it all up and get €30

QED

Professor_Fink

sd123 wrote:

3 men go into a bar and order a round of drinks, it comes to 30 euro. each man pays 10 euro. after a while, the barman realises he made a mistake, the drinks should've costed 25 euro. he comes down with the extra 5 euro to refund them. the men decide that it was too awkward to split up 5 euro between 3 people and each decides to take 1 euro and gives the extra 2 euro to the barman as a tip. now each man paid 9 euro and the barman gets 2 euro. that makes 3(9) + 2 = 29 euro, wheres the extra 1 euro gone?????
...
can anyone explain this to me:o

The reason for the confusion is that 25 euro does not divide evenly between 3 people. Giving a 2 euro tip brings the total up to 27 euro, which does divide evenly, and so each person gets 1 euro back. 3*9 is what they paid (including the 2 euro tip) and they got 3 euros back, making up a total of 30.

maxi-twist

Why would you tip the barman if he overcharged you. Idiots!

Carsinian Thau

maxi-twist wrote:

Why would you tip the barman if he overcharged you. Idiots!

It's a maths riddle. Only the figures need to make sense.

mathias

now each man paid 9 euro

This is the key part , you need to keep an eye on how much they paid at all times ( regardless of whether they know it or not ) and it works out fine.

Originally it was 30 , then it was 25 , so that was 8.333... each , then it was 9.3333... each , after getting the one back , and then the 2 tip makes 30.

Instead of the decimals its better to leave in Surd form as its more accurate , so originally it was 10 each , then 8 and 1/3 each , then 9 and 1/3 each , and the 2 euro tip makes it 3 x 9 and 1/3 which makes 28 and 2 euro tip = 30.

The mistake that leads to the discrepancy is assuming they paid 9 each at some point ,( which comes from an incorrect subtraction instead of a correct addition ) , they never did.

fluppet

You're probably all saying the same thing, but the TV is on in the background so I can't concentrate.

Here's my explanation, anyway:

The question is trying to trick you.

You are not trying to get to 30... you are now trying to get to 25.

They pay 9 each = 27
This includes 2 tip, so deduct it from the above to get 25 - the real price.

If you do want to get back to the 30:
Why would you add the 2? It's the 3 you should be adding - they paid 27 (including 2 tip to barman) with the 3 back from the barman. So that's 27+3 = 30.

The 2 thing is just to confuse you - all that happens is they pay 10 each, and then receive 1 each back. So they pay 27 after the barman returns 3.