Monday, August 31, 2009

Short changed

Three men go to a hotel. They pay for a $30 room to share, each giving $10. Later the manager realizes that the room was only $25 and so gives $5 to the bellboy to return to the men. The bellboy takes the $5 to the men. They give the bellboy $2 as a tip. Just after the bellboy left, one of the men says, "We each spent $9 just now, since we each got back $1, and we gave the bellboy $2, that's $29". Where's the missing $1?

This must have been a long time ago.

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17 Comments:

Anonymous Anonymous said...

Each person paid $9, totalling $27. The manager has $25 and the bellboy $2.
The bellboy's $2 should be added to the manager's $25 or subtracted from
the tenants' $27, not added to the tenants' $27.

August 31, 2009 4:16 PM  
Blogger Chris said...

Oh dear, these problems are being gobbled up as fast as I can spew them out.

Anonymous, was that a hat-trick? I'm seeing a sharp mind at work tonight.

August 31, 2009 4:23 PM  
Anonymous Anonymous said...

Aussie boy here again - I'm on a roll!
There is no missing $1. The men pay $9 each, that's $27. The manager has $25 and the bellboy $2. The confusion seems to be where the $2 tip came from - it adds to the room rent of $25, not to the men's contribution 0f $27.

August 31, 2009 4:23 PM  
Anonymous Anonymous said...

Boy from Oz here: No, I missed the hat-trick by 7 minutes!

August 31, 2009 4:25 PM  
Blogger Chris said...

Looking like it could be two sharp minds.

August 31, 2009 4:25 PM  
Blogger Chris said...

I won't hold it against you. I know you didn't cheat.

August 31, 2009 4:26 PM  
Anonymous Anonymous said...

Actually, I did get the hat-trick: water jug, xth root and marbles puzzles, but just too slow to claim the room rent one.
Keep sending them - I love this!

August 31, 2009 4:28 PM  
Blogger Chris said...

I'd forgotten I'd posted that. I'll take a gander.

August 31, 2009 4:30 PM  
Blogger andrew said...

it`s true the three tenants spent $9 each thus totaling up to $27. this total is inclusive of the amount for the room($25) and the tip for the bellyboy($2)

September 1, 2009 2:35 AM  
Blogger §♥☻◙ scrapped prince ◙☻♥§ said...

this problem is so totally nooby.. there's no $1 missing... my relatives already asked me a problem like this and i proved it that there's no missing $1

September 1, 2009 3:24 AM  
Blogger Chris said...

I do like explanatory answers. Thanks andrew. Not sure what the next post was about though.

September 1, 2009 6:56 AM  
Anonymous Anonymous said...

This particular problem seems to show up about every 2 to 3 months on here.. lol

September 1, 2009 1:45 PM  
Anonymous Anonymous said...

I am the anonymous who sent in the first post. I am completely hopeless at maths. I don't know how I got the answer right. Apologies to anonymous from Oz for getting in first.

I cannot really understand why I like these puzzles so much. I very rarely work out the maths ones, although I do love thinking outside the box.

Chris, keep sending in your conundrums. I cant do them, but I admire people who can.

September 1, 2009 3:21 PM  
Blogger Chris said...

Hi Anonymous, thanks for you remarks. As with too any I've posted, they are too well known.

Some of the logic / seeming paradoxes are quite good.

Trouble is I like the calculus and complex number types best. But I realise that's not fair on the visitor's who are too young to have done that stuff. So I'm trying to aim for different levels.

I can't think up the logic types. It's easier, for me,to think up maths/physics one's (so far!)

September 1, 2009 4:07 PM  
Anonymous Anonymous said...

if they originally paid $30 and got back $5 they each got $1 back and gave a $2 tip, if you add it up there is no missing dollar.

September 2, 2009 7:28 PM  
Blogger Chris said...

Hi Anonymous. Your sentence isn't clear about what you're adding up.
It could still be interpreted as 30-3+2 = 29 => missing dollar or it could be interpreted as 30-5+2 = 27 = 3*9 (which of course is the correct way to do it). But notice no-one says $3 is now missing. It's partly psychological. It is a cunning misdirection problem though.

However, I'm sure you know what you meant and that you are doing it right really. Goodnight.

September 2, 2009 9:04 PM  
Blogger Chris said...

Of course, the men have each paid $(8+1/3) for the room and $(2/3) for the tip => $9 total.

September 3, 2009 5:03 AM  

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