UPSC Maths Problems Challenge : A Problem A Day! (Day 11)

Today's problem is very similar to that of the 5th day problem challenge (you can read it here) but this,as I read it was asked in the interview part of the IAS exam and hence does not have options.However,it is a very interesting problem indeed and it is weird that such a small,simple problem can confuse you completely!Read on to find out the solution.

(Original Photograph Source)

Today's Problem(23/06/2015)

Question Credit : http://gpuzzles.com/

(Grammatical Errors Corrected)

I purchase perfume from a store and give the shopkeeper a thousand rupee note.

The perfume cost Rs.300.

Since the store person does not have any change, he gets the change from next shop and returns me 800 rupees.

After a while, the next shopkeeper comes and told the 1st shopkeeper that the note is a fraud and takes his money back.

How much loss does the 1st shopkeeper have to bear ?

The shopkeeper gives me extra ₹ 100 (i.e ₹ 800 instead of ₹ 700).So,he already has a loss of  ₹ 100.Now,he has to give the other shopkeeper ₹ 1000 since the note is a fake one and hence has no value.So,the total loss suffered by the first shopkeeper is ₹ (1000 + 100) = ₹ 1100.