What is the loss?

[needimprovement]

A guy buys a chocolate (from a shop) worth 80 YEN and hands over 100 YEN to the shopkeeper. The Shopkeeper doesn't have 20 YEN to give back the guy. Hence, he goes to the adjacent shop, asks for an exchange to a lady at the cash counter and fortunately he is able to convert 100 YEN into 10 numbers of 10 YEN. He comes back and returns the 2 numbers of 10 YEN to the guy. The guy leaves happily with the chocolate. After an hour or so, the lady from the adjacent shop finds the particular 100 YEN to be a fake one and promptly returns it and takes back a good 100 YEN from the Shopkeeper.

(Hope I somehow managed to put it across)

 

What is the loss for the poor Shopkeeper?

Edited August 26, 2010 by needimprovement

[Sisyphus]

 

He loses 100 yen. Just add up what he gains in trade minus what he loses: In trades, he gains a total of 2 fake 100 yen and 10*10 real yen for a total of 100 yen real value. He loses a candy bar worth 80, 2 10 yen, 1 fake 100 yen, and 1 real 100 yen, for a total of 200 total value.

 

Of course, that's assuming the fake 100 yen is entirely worthless...

 

 

[Mr Skeptic]

He loses 100 yen. He gains 100 yen from the store keeper. 20 yen he gives to the man, 100 yen he gives to the store keeper, 20-60 yen he loses for buying the chocolate bar, and the remainder he loses as opportunity cost (assuming the other man would have bought the chocolate with real money)

[CaptainPanic]

 

He loses 20 YEN and a chocolate bar.

He stands at minus 1 chocolate, and plus 80 YEN at first. Then he loses 100 YEN, resulting in minus one chocolate and minus 20 YEN.

 

He may sell the chocolate for 80 YEN, but if he's a good shopkeeper, the value of the bar is less than 80 YEN... and the difference between what the shopkeeper paid, and what his customers pay is called "profit". A lack of profit is not a loss. So, I must conclude that we don't know the monetary value of the loss. It's just 1 chocolate bar and 20 YEN.

 

[blanchardd]

Who would pay for a bar of chocolate with counterfeit money when it is a little more than a dollar?

[DJBruce]

The problem never says that the customer knowingly passes counterfeit currency. They just as well could have unknowingly pay with it, and the intentions or lack of intentions of the customer really has no effect on the problem itself.

 

As for the puzzle itself:

 

The shopkeeper loses 100 yen. The transactions between the two shopkeepers add up so there was no money actually changing hands. So the only place the shopkeeper can loss money is from his dealings with the customer. When the customer comes in he has no actual money. When the customer leaves the shop they have a candy bar worth 80 yen and 20 yen in change. So since the customer made 100 yen in profit the shopkeeper lost 100 yen.

 

Edited August 26, 2010 by DJBruce

[Siderney_Mello_Pops]

He loses 100 yen...but I'm still confused as to why the guy would bother to make counterfit money that's worth about a dollar.....