Thursday, March 29, 2012

mystery discount


(I first posted this puzzle in 2009.  You all have gotten better at math since then right?)

So these three guys go have lunch together and order the same item.  Everybody puts in $10.00 and gives it to the waiter.  He goes back to the cash register with the $30.00 and the manager tells him, "Oh, there is a special today their bill will only be $25 so give them $5.00 back.
Now the waiter is thinking $5.00 split three ways will be a problem so he pockets $2 and gives each customer $1.00.
So to summarize:
Each of the customers (3) paid $9.00 = subtotal $27.00
The waiter has $2.00 in his pocket
grand total $27 + $2 = $29

Where did the missing dollar go?

I think Bernie Madoff got it.

I wonder if Bernie used this type of accounting on those statements he gave out to his clients sucker victims.

My dad loved to tell this puzzle.  I think he really liked my reaction because in high school I really enjoyed math and started taking courses he never had.  He enjoyed the frustration the puzzle gave me.  He also enjoyed beating me in cribbage and counting the points faster than I could.

One problem with this puzzle today is finding a $10.00 lunch at a restaurant with a waiter.  That's harder than finding the missing dollar.  So here's an updated version with even more money missing:

3 guys stop in a coffee shop and order the same drink.  As in the other version, they each give the waiter $10.  As the waiter enters the items, he discovers the menu didn't show the new discounted prices and the total comes out to $23.00.  Like in the other story, he doesn't want the confusion of dividing the change and decides to take a little.  He pockets $1.00 and gives each customer $2.00.
Let's summarize:
3 guys paid $8 each = subtotal $24.00
waiter has $1 in his pocket
grand total $24 + $1 = $25
Now we are missing $5.00 and who's on first.

Maybe I could get an accounting job.  Oh have you done your taxes yet?
(if you are really wanting to know I'll put an answer in the comments later - so check back) 

21 comments:

oceangirl said...

I have wikied for the answer, just like I wikied Madoff!

OneStonedCrow said...

uhm yeah, maths was never my strong point - I got 12% in my final year at school ... I'll just wait for you to publish the answer ... please ...

Barbara said...

I used to be good at math, but that was a long time ago. I'll check back for the answer... :)

Bearmancartoons said...

$25/3 = $8.33.  Add the $1 to each and that is $9.33.  $9.33x3=$28.  No missing dollar and i didn't look it up.....woo hoo.

lisleman said...

 You get $30 when you add the waiter's $2.  Ok, but each guy did not "pay" $9 1/3.  Your $28 total is a combination total of paid to the store and rebated money I guess.  That's not the way I explain it.  I'll explain in my Friday Fragment post.  Your numbers add up but just seem to be an odd combination to get to $30.  Each guy still paid $9 and the 3 of them total $27.  It would have been so fun to watch my dad argue with you on your answer.
thanks.

lisleman said...

 From your blog I recall that you do (or did) work as a waitress.  This is a fun puzzle for the staff.    I'll explain it in my Friday Fragment post.  thanks

lisleman said...

  I'll explain it in my Friday Fragment post.  thanks

lisleman said...

  I'll explain it in my Friday Fragment post.  "wikied" - hmmm - I have used "googled" but not the wikipedia verb.  thanks

unknownmami said...

I haven't done my taxes yet and I'm not letting you anywhere near them. 

lisleman said...

Hey a little for me and little for you and less for the government - that's our slogan here at Lisleman's Loose No Loss Accounting and Hair Restoration Services.
Please could you be our first customer?
thanks

Frau said...

I need more coffee to answer this one.....no said there was a quiz today! 

Joanne said...

My dad used to have eleven fingers, too.  10,9, 8, 7, 6 plus five on the other hand are 11 fingers.

lisleman said...

 I can get a good deal on a cup of coffee if we travel in a group of three.  You don't like pop quizzes?  I didn't mind in school but I've been upset by pop quizzed my wife has given at times.
thanks

lisleman said...

 Yes I remember that one too.  I need to remember that one for my grand kids.  thanks

CaliforniaGirl500 said...

When it comes to math, I am the WORST.  But, without reading any comments, my question is "Why aren't you counting the $3 he gives back?"  

lisleman said...

You are thinking about the right idea - accounting.  I say that the $3 is considered since the amount each paid is now $9 instead of $10.
I'll be posting the explanation later tonight.  thanks

JillsyGirl said...

I'm with Barbara on this.  I "was" good at math, until something like this comes up.  My Dad used to get me on the "Which is heavier....a lb. of rocks or a lb. of feathers?"  I used to argue with him over it!! :-)

lisleman said...

 Jillsy you carry that pound of feathers and I'll take the 1/2 pound of rocks - Ok?  You are in luck.  I just posted my Friday Fragment post and the explanation is in it along other great stuff.
thanks

Mrs4444 said...

I never did like math that much. 
Good idea, Lisa!
We have our taxes done by a professional (further evidence that I don't like math). Our new paint and carpet will be paid for with tax money, in large part. :)

lisleman said...

 That's good use of the tax refund.  I have found the turbotax software very good.  thanks

Mrs4444 said...

I'll be tempted to try that next year...

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