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        riddles >> medium >> Where has 1 rupee gone
        
(Message started by: checker on Nov 26^th, 2006, 10:20pm)

Title: Where has 1 rupee gone
Post by checker on Nov 26^th, 2006, 10:20pm

Nothing you can do with math applies after reading this. I think that all structural calculations I have ever done are now invalid because of the flawed system.

Three guys in a hotel call room service and order two large Pizzas. The delivery boy brings them up with a bill for exactly Rs.30.00. Each guy gives him a Rs. 10.00 bill, and he leaves. That's fact! When he hands the Rs. 30.00 to the cashier, he is told a mistake was made. The bill was only Rs.25.00, not Rs. 30.00. The cashier gives the delivery boy five Rs. 1.00 Notes and tells him to take it back to the 3 guys who ordered the pizza. That's fact!

On the way back to their room, the delivery boy has a thought. These guys did not give him a tip. He figures that since there is no way to split Rs. 5.00 evenly three ways anyhow, he will keep two Rupees for himself and give them back three Rupees. OK! So far so good!

He knocks on the door and one fellow answers. He explains about a mix up in the bill, and hands the guy the three rupees, and then departs with his two-rupees tip in his pocket.

Now the fun begins!

Remember Rs 30- Rs 25= Rs 5 Right? Rs 5- Rs 3= Rs 2 Right? So what's the problem?

All is well, right? Not quite.

Answer this: Each of the three guys originally gave Rs.10.00 each. They each got back Rs 1.00 in change. That means they paid Rs 9.00 each, which times three is Rs 27.00. The delivery boy kept Rs 2.00 for a tip. Rs 27.00 plus Rs 2.00 equals Rs 29.00. Where the hell is the one Rupee?

If you get the answer, pls reply me bcoz i m also searching for it!!!!

Title: Re: Where has 1 rupee gone
Post by Three Hands on Nov 26^th, 2006, 10:28pm

I know the answer, but (following a quick search) I reckon http://www.ocf.berkeley.edu/~wwu/cgi-bin/yabb/YaBB.cgi?board=riddles_hard;action=display;num=1149560883;start=2#2 explains it better than I could.

Title: Re: Where has 1 rupee gone
Post by THUDandBLUNDER on Nov 26^th, 2006, 11:01pm

You are wrongly assuming that 27 + 2 should equal 30.
But R27 has been paid out, the hotel has R25, and the delivery boy has R2.
That's all there is to it.

Let the 3 men pay a total of 3m
Let the overcharge be x
Let x be of the form 3n + d where d is the amount that the delivery boy keeps
The delivery boy gives back 3n to the men so that they have now paid 3m - 3n in total
The problem says that 3m - 3n + d should equal 3m
This is only true when d = 3n
But in your problem d = 2 and 3n = 3

(All variables are positive integers.)

Title: Re: Where has 1 rupee gone
Post by Sameer on Nov 27^th, 2006, 9:07am

Or in a simpler way... the total of 27 includes the bill 25+tip 2. And the three they get back makes up for 30.

Title: Re: Where has 1 rupee gone
Post by THUDandBLUNDER on Nov 27^th, 2006, 12:44pm

on 11/27/06 at 09:07:59, Sameer wrote:

Or in a simpler way... the total of 27 includes the bill 25+tip 2. And the three they get back makes up for 30.

As I see it, the correct argument merely replaces rather than refutes the incorrect argument of the problem statement. Hence my simple algebra.

Title: Re: Where has 1 rupee gone
Post by checker on Nov 28^th, 2006, 9:20pm

on 11/26/06 at 23:01:36, THUDandBLUNDER wrote:

But in your problem d = 2 and 3n = 3

Actually my problem is this only that if am having solid numerical data I can have interpretations but what if i am algebrically solving then what....

Title: Re: Where has 1 rupee gone
Post by Icarus on Nov 29^th, 2006, 7:22am

on 11/28/06 at 21:20:29, checker wrote:

Actually my problem is this only that if am having solid numerical data I can have interpretations but what if i am algebrically solving then what....

???

Would you mind expressing that in english?