Previous in Forum: Most Unlikely Movie Scientists   Next in Forum: Infrared LEDs as Heaters
Close
Close
Close
15 comments
Rate Comments: Nested
Active Contributor

Join Date: Dec 2006
Location: Dublin & Santa Fe
Posts: 10

Outsmarted by a 12-year-old!

10/10/2007 2:09 PM

My 12-year-old came to me with this problem and I can't figure it out. It's late, though, so I must be missing something very simple. Maybe a Guinness will help me...

1) Three friends went out to dinner and the bill came to €30

2) They each gave the waiter €10 (3 x €10 = €30)

3) The waiter took the money to the Teller at the register

4) The Teller noticed that the bill was only €25

5) The Teller gave the Waiter €5 back (€30 - €25)

6) The Waiter gave €1 back to each diner (total of €3)

7) The Waiter kept the remaining €2 (€5 – €3)

8) Each diner gave waiter €10, got back €1, so the net spend each is €9

9) Three diners in total spent €27 (3 x €9 = €27)

10) The Waiter kept €2

11) The Total accounted for is €29 – where is the missing €1?

__________________
jadien
Register to Reply
Pathfinder Tags: puzzle
Interested in this topic? By joining CR4 you can "subscribe" to
this discussion and receive notification when new comments are added.

Good Answers:

These comments received enough positive votes to make them "good answers".
3
Guru
Hobbies - HAM Radio - New Member Hobbies - Model Rocketry - New Member

Join Date: Jan 2007
Posts: 787
Good Answers: 52
#1

Re: Outsmarted by a 12-year-old!

10/10/2007 2:51 PM

Step ten and eleven are your problem. The diners spent 27 not 30, why are you trying to get back to 30.

The error is that the bill was 25, and the waiter kept 2 for a total of 9 each for 27 spent, end of story.

If you add 2 to 27, then your adding in the two in twice for no reason other than to get back to 30 for no reason, which is not what they spent since they each got a dollar back.

You should be trying to get back to 27, and you did that in step nine.

If you want to add anything you should add 3 for the money they got back to account for the 30

Register to Reply Good Answer (Score 3)
Guru
Canada - Member - Our strength is our diversity

Join Date: Jan 2007
Location: Canada
Posts: 1024
Good Answers: 40
#2

Re: Outsmarted by a 12-year-old!

10/10/2007 3:00 PM

there is no missing €1

The meal cost €25 + €2 tip = 27

27 divide by 3 = 9

the error is the last statement "The Total accounted for is €29" What the diners spent included the waiters tip.

__________________
Perfection is a subjective and abstract concept.
Register to Reply
Active Contributor

Join Date: Dec 2006
Location: Dublin & Santa Fe
Posts: 10
#3

Re: Outsmarted by a 12-year-old!

10/10/2007 3:34 PM

Thanks, I get it now; once the money is given back to the diners by the waiter the €30 is not relevant; €27 is. The next problem is how to explain this to my 12-year old so that he can explain it to his friends tomorrow.

__________________
jadien
Register to Reply
Guru
Canada - Member - Our strength is our diversity

Join Date: Jan 2007
Location: Canada
Posts: 1024
Good Answers: 40
#4
In reply to #3

Re: Outsmarted by a 12-year-old!

10/10/2007 3:46 PM

In the statement the "the money accounted for was $29" was a deliberate diversion from the truth. It included the Tip twice; What the diners paid (diner + tip) then added it again to mislead a person to add to 30.

The 30 dollars was mentioned numerous times in the leading steps. It was also set up in the first lines as a reference total. This is a "trick" used by magicians and mentalists and sales persons to make a person think of a number. They also did all the math for you so you would trust them and and they could sneak in the deception.

__________________
Perfection is a subjective and abstract concept.
Register to Reply
Guru

Join Date: Jul 2007
Location: 30°30'N, 97°45'W, Elv: 597 ft.
Posts: 2410
Good Answers: 10
#5
In reply to #4

Re: Outsmarted by a 12-year-old!

10/10/2007 3:49 PM

you forgot politicians and the media!

And my ex-wife.

__________________
I never apologize. I'm sorry that's just the way I am.
Register to Reply
Guru
Canada - Member - Our strength is our diversity

Join Date: Jan 2007
Location: Canada
Posts: 1024
Good Answers: 40
#6
In reply to #5

Re: Outsmarted by a 12-year-old!

10/10/2007 3:59 PM

Are you nagging me? I always try to forget the politicians. I am an optimist.

The media are the ultimate experts in brainwashing and even Machiavelli could have taken lessons from them.

As far as your Ex goes... I know nOthing

__________________
Perfection is a subjective and abstract concept.
Register to Reply Off Topic (Score 5)
Power-User

Join Date: Oct 2007
Location: third rock from Sol
Posts: 121
#7
In reply to #4

Re: Outsmarted by a 12-year-old!

10/10/2007 5:20 PM

That' why they put up signs that say 'watch your hat and coat' at the entrance to the restaurant.

So you wont notice the slight of hand

keep one eye on the coat rack and one on the wallet, lmao.

__________________
I'm not a real engineer, I just play one on TV
Register to Reply
Anonymous Poster
#8

Re: Outsmarted by a 12-year-old!

10/10/2007 11:28 PM

The boy has really outsmarted you by adding €2(of waiter) to €27 (net total expenditure) in stead of subtracting it from €27 i.e. 27-2=25 paid agianst bill.

Register to Reply
Guru
United Kingdom - Member - Indeterminate Engineering Fields - Control Engineering - New Member

Join Date: Jan 2007
Location: In the bothy, 7 chains down the line from Dodman's Lane level crossing, in the nation formerly known as Great Britain. Kettle's on.
Posts: 32175
Good Answers: 839
#9

Re: Outsmarted by a 12-year-old!

10/11/2007 5:21 AM

Is this is an example of something called the 'short con'? Someone making €1 out of it?

__________________
"Did you get my e-mail?" - "The biggest problem in communication is the illusion that it has taken place" - George Bernard Shaw, 1856
Register to Reply
Guru
United Kingdom - Member - Indeterminate Engineering Fields - Control Engineering - New Member

Join Date: Jan 2007
Location: In the bothy, 7 chains down the line from Dodman's Lane level crossing, in the nation formerly known as Great Britain. Kettle's on.
Posts: 32175
Good Answers: 839
#10

Re: Outsmarted by a 12-year-old!

10/11/2007 5:42 AM

Ahah!

Withhold the missing €1 from the youngster's pocket money until the solution to the problem has been demonstrated!

__________________
"Did you get my e-mail?" - "The biggest problem in communication is the illusion that it has taken place" - George Bernard Shaw, 1856
Register to Reply
Active Contributor

Join Date: Dec 2006
Location: Dublin & Santa Fe
Posts: 10
#11
In reply to #10

Re: Outsmarted by a 12-year-old!

10/11/2007 5:56 AM

Good plan - I like that one!

__________________
jadien
Register to Reply
Guru
Popular Science - Weaponology - Scapolie, new member.

Join Date: Jan 2007
Posts: 1058
Good Answers: 8
#12

Re: Outsmarted by a 12-year-old!

10/11/2007 6:30 AM

Hi JaDien, This is the oldest puzzle in the book, our teacher 50 years ago asked us this question, and asked us to come up with the right answer the next day. The diners actually paid £9.66p each! Spencer.

Register to Reply Score 1 for Off Topic
Participant

Join Date: Sep 2007
Posts: 3
#13

Re: Outsmarted by a 12-year-old!

10/11/2007 10:13 PM

The total amounts to 27, from there 2 pounds is the tip d.i. 27+3 equals 30. In point 11, 9x3=27 not 29 as you indicated. There is no catch, 3x1 is not 1 but3.

Kind of easy

Register to Reply
Associate

Join Date: Oct 2007
Posts: 25
Good Answers: 1
#14

Re: Outsmarted by a 12-year-old!

10/13/2007 6:35 AM

Actually the trick is in how much they each paid. Once the bill came to 25 then EACH person paid 8.33. With the dollar refund it came to 9.33 each which totals 28 plus the tip equals 30. Now bring on the 13 year old.

Register to Reply
Associate

Join Date: Jun 2008
Location: Right next to the lizard king.
Posts: 39
#15

Re: Outsmarted by a 12-year-old!

09/25/2008 6:47 AM

The bill was only 25. 25 divided by 3=8.33. This is what they paid. The tip was 2. 2 divided by 3=.666 per diner. 8.33+.66 = 9*3= 27 This is what each paid equaling out to 27 + the 3 dollars given back = 30.

I got nuthin

__________________
If I'm 10 minutes early, then I'm only 5 minutes late. Cletus
Register to Reply
Register to Reply 15 comments

Good Answers:

These comments received enough positive votes to make them "good answers".
Copy to Clipboard

Users who posted comments:

Anonymous Poster (1); clevis1 (1); frankd20 (1); Hellcat (1); JaDieN (2); joltnjny (1); PWSlack (2); Scapolie (1); siegenjolu (1); techno (3); TexasCharley (1)

Previous in Forum: Most Unlikely Movie Scientists   Next in Forum: Infrared LEDs as Heaters

Advertisement