Author Topic: Brain Twister need help  (Read 5471 times)

onlyme

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Brain Twister need help
« on: October 12, 2006, 04:56:07 PM »
Okay this might not last to long but it has to do with the gym.  Okay three guys come into the gym and wanted to train for the day.  They each only have $10. They ask the guy how much for all three of them and he say $30.  They say great and handed the guy $10 each for the $30.  They go inside and start to train.  Well the manager comes out and recognizes the guys and asked how much they paid.  The first desk guy says $30 for all three.  He says well no they live here give them a deal.  Do it for $25 he says, then tell the guy to give them $5 back.  So he goes over and hands the guys $5.  They say here dude you can keep $2. 

At the beginning it cost the guys $10 each to train.  After the refund they each got back a dollar.  So it actually cost them just $9 each.  Now add the $2 they gave the front desk guy, that adds up to $29.  What happened to the other dollar?

MisterMagoo

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Re: Brain Twister need help
« Reply #1 on: October 12, 2006, 05:04:17 PM »
add it up differently. don't look at it in terms of "how much they paid" and such, look at it in terms of where the actual money is.

at the end, the gym keeps $25, the guys have a dollar each, and the guy at the front desk has $2. thats 25 + 1 + 1 + 1 + 2 = 30. the problem is when you start trying to add up real money with "amount paid" and you get jumbled up.

onlyme

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Re: Brain Twister need help
« Reply #2 on: October 12, 2006, 11:27:29 PM »
add it up differently. don't look at it in terms of "how much they paid" and such, look at it in terms of where the actual money is.

at the end, the gym keeps $25, the guys have a dollar each, and the guy at the front desk has $2. thats 25 + 1 + 1 + 1 + 2 = 30. the problem is when you start trying to add up real money with "amount paid" and you get jumbled up.

Yes but when you do it any other way it adds up to $29.  Why and where does it go.  All I know is each guy ended up paying $9 each and with the guy getting $2 it only adds up to $29.  Explain where it goes.

gordiano

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Re: Brain Twister need help
« Reply #3 on: October 12, 2006, 11:29:19 PM »
It probably ended up in Shawn Ray's pocket.............
HAHA, RON.....

AVBG

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Re: Brain Twister need help
« Reply #4 on: October 12, 2006, 11:32:37 PM »
Okay this might not last to long but it has to do with the gym.  Okay three guys come into the gym and wanted to train for the day.  They each only have $10. They ask the guy how much for all three of them and he say $30.  They say great and handed the guy $10 each for the $30.  They go inside and start to train.  Well the manager comes out and recognizes the guys and asked how much they paid.  The first desk guy says $30 for all three.  He says well no they live here give them a deal.  Do it for $25 he says, then tell the guy to give them $5 back.  So he goes over and hands the guys $5.  They say here dude you can keep $2. 

At the beginning it cost the guys $10 each to train.  After the refund they each got back a dollar.  So it actually cost them just $9 each.  Now add the $2 they gave the front desk guy, that adds up to $29.  What happened to the other dollar?

You ate it.. you greedy bastard  ;D

tommywishbone

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Re: Brain Twister need help
« Reply #5 on: October 13, 2006, 01:13:18 AM »
That's one of my favorite old riddles. I actually tell it with 3 guys checking into a hotel...

It's semantics. There is no missing dollar. :) But if there was a missing dollar, I bet Lou Ferrigno has it.
a

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Re: Brain Twister need help
« Reply #6 on: October 13, 2006, 01:20:10 AM »
I didnt want to sleep tonight anyway  >:(

tweeter

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Re: Brain Twister need help
« Reply #7 on: October 13, 2006, 01:34:30 AM »
Yes but when you do it any other way it adds up to $29.  Why and where does it go.  All I know is each guy ended up paying $9 each and with the guy getting $2 it only adds up to $29.  Explain where it goes.
The $2 that the guy at the front desk has is already included in the $9 that the three guys paid; the 3 missing dollars is in the pockets of the three guys.

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Re: Brain Twister need help
« Reply #8 on: October 13, 2006, 01:36:18 AM »
The $2 that the guy at the front desk has is already included in the $9 that the three guys paid; the 3 missing dollars is in the pockets of the three guys.

9 x 3 = 27 + 2 = 29   :o

jwb

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Re: Brain Twister need help
« Reply #9 on: October 13, 2006, 01:43:49 AM »
think of it this way:

they start paying $10 each,

they then get back one third of $5 which is $1.67 each.

they decide to tip the guy $2 so they give back 1/3rd of $2 each which is 67 cents each so they now have $1 each.

so they end up with $1 each, the guy gets his $2 and the gym their $25

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Re: Brain Twister need help
« Reply #10 on: October 13, 2006, 01:51:50 AM »
Okay, so a guy needs a website, but he only has $300...

jwb

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Re: Brain Twister need help
« Reply #11 on: October 13, 2006, 01:52:16 AM »
or,

they actually end up paying the gym one third of $25 = $8.33 each

they end up with $1 each so $9.33 is now accounted for out of the original $10.

the remaining 67 cents each goes to the kid

8.33
1.00
0.67
----
10.00 each

Bigger Business

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Re: Brain Twister need help
« Reply #12 on: October 13, 2006, 01:52:38 AM »
Okay, so a guy needs a website, but he only has $300...

minus the $25 referral...

jwb

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Re: Brain Twister need help
« Reply #13 on: October 13, 2006, 02:04:45 AM »
or,

the gym gets $25 total

the guys get $3 total

the kid gets $2 total

equals $30

okay now i'm being silly

onlyme

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Re: Brain Twister need help
« Reply #14 on: October 13, 2006, 02:12:13 AM »
think of it this way:

they start paying $10 each,

they then get back one third of $5 which is $1.67 each.

they decide to tip the guy $2 so they give back 1/3rd of $2 each which is 67 cents each so they now have $1 each.

so they end up with $1 each, the guy gets his $2 and the gym their $25

That would work but it was done exactly as I said.  They each had a $10 bill.  And when the guy came back to give them somemoney back, he handed them a dollar each and he kept $2.  There was no change to give.

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Re: Brain Twister need help
« Reply #15 on: October 13, 2006, 02:25:36 AM »
or,

the gym gets $25 total

the guys get $3 total

the kid gets $2 total

equals $30

okay now i'm being silly

O forgot to mention they were training Shoulders and calves

rocket

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Re: Brain Twister need help
« Reply #16 on: October 13, 2006, 03:16:21 AM »
O forgot to mention they were training Shoulders and calves

I'm reliably informed there was supersetting involved.

Seriously, what is the question in this thread onlyme, JWB explained it perfectly.

jwb

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Re: Brain Twister need help
« Reply #17 on: October 13, 2006, 03:20:15 AM »
I'm reliably informed there was supersetting involved.

Seriously, what is the question in this thread onlyme, JWB explained it perfectly.
yeah what is the question? $25 for the workout, $2 for the kid, $3 for the guys.

you can't add it up from the end because of the sequence involved...

The Luke

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Re: Brain Twister need help
« Reply #18 on: October 13, 2006, 03:38:12 AM »
Onlyme,

It's a logical fallacy brain twister... developing a specific train of thought, then depending on the natural unwillingness of people to abandon/re-evaluate the initially developed model when back-engineering the problem.

Each guy pays $10... that's $30 between them.

The gym owner returns $5... now each guy has payed 25/3 dollars (that's $8.33 for a total of $25 between them).

Each guy now contributes 2/3 ($0.66) of a dollar towards the guys tip.


Now add it up properly:

Each guy payed $8.33 to work out... that's a total of $25
Each guy contributed $0.66 towards the desk clerks tip.... that's $2 between them for a total of $27.

So, as a group the guys have payed $25 towards working out, $2 towards the tip... making a total of $27 between them. The $27 payed out, plus the net $3 the gym refunded them (refund minus the tip) equals the $30 originally payed out.

Paying out $27 ($25 plus $2 tip) is the same as paying out $30 and getting $3 back (a dollar each refund).

The total payed out ($30) is equal to:
The total amount each payed (cost plus tip) combined with the refund...
NOT
The total amount each payed plus the tip... that way you're just adding the total payed ($25 plus $2) and the tip. Adding the tip twice to $25 will always give you $29 no matter which way you add it up.

The wording of the brain teaser and the use of an intermediary to confuse the transaction encourages people to think in terms of adding the net cost (cost plus tip) to the tip... getting $29. You should add the net cost (cost plus tip) to the refund ($3)... thereby arriving at the amount originally handed over ($30).


Hope this helps,
The Luke

jwb

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Re: Brain Twister need help
« Reply #19 on: October 13, 2006, 03:42:23 AM »
Onlyme,

It's a logical fallacy brain twister... developing a specific train of thought, then depending on the natural unwillingness of people to abandon/re-evaluate the initially developed model when back-engineering the problem.

Each guy pays $10... that's $30 between them.

The gym owner returns $5... now each guy has payed 25/3 dollars (that's $8.33 for a total of $25 between them).

Each guy now contributes 2/3 ($0.66) of a dollar towards the guys tip.


Now add it up properly:

Each guy payed $8.33 to work out... that's a total of $25
Each guy contributed $0.66 towards the desk clerks tip.... that's $2 between them for a total of $27.

So, as a group the guys have payed $25 towards working out, $2 towards the tip... making a total of $27 between them. The $27 payed out, plus the net $3 the gym refunded them (refund minus the tip) equals the $30 originally payed out.

Paying out $27 ($25 plus $2 tip) is the same as paying out $30 and getting $3 back (a dollar each refund).

The total payed out ($30) is equal to:
The total amount each payed (cost plus tip) combined with the refund...
NOT
The total amount each payed plus the tip... that way you're just adding the total payed ($25 plus $2) and the tip. Adding the tip twice to $25 will always give you $29 no matter which way you add it up.

The wording of the brain teaser and the use of an intermediary to confuse the transaction encourages people to think in terms of adding the net cost (cost plus tip) to the tip... getting $29. You should add the net cost (cost plus tip) to the refund ($3)... thereby arriving at the amount originally handed over ($30).


Hope this helps,
The Luke
exactly you were double counting the $2 tip

Jr. Yates

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Re: Brain Twister need help
« Reply #20 on: October 13, 2006, 12:22:46 PM »
It probably ended up in Shawn Ray's pocket.............
hahahaha!  hahahahaha!
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Re: Brain Twister need help
« Reply #21 on: October 13, 2006, 12:30:06 PM »
It's semantics. There is no missing dollar. :) But if there was a missing dollar, I bet Lou Ferrigno has it.


HAHAHAHA!!
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MisterMagoo

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Re: Brain Twister need help
« Reply #22 on: October 13, 2006, 12:42:30 PM »
Yes but when you do it any other way it adds up to $29.  Why and where does it go.  All I know is each guy ended up paying $9 each and with the guy getting $2 it only adds up to $29.  Explain where it goes.

it doesn't go anywhere because any other addition isn't actually adding up money. it's multiplying "net sum paid" instead of actual dollars trading hands. it's just a little math trick. you add up the wrong numbers.

you're right that they only paid $27, but the thing is that the $2 the guy got is a part of that $27. that's $25 to the desk and $2 to the guy, add up the $3 the lifters kept and that's $30.

what you're doing is adding up the $2 the one guy kept twice and ignoring the $3 refund entirely. the guys paid $27 and they kept $3. that's $30 by my count.

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Re: Brain Twister need help
« Reply #23 on: October 13, 2006, 12:53:27 PM »
God damn people......  >:(  >:(  >:(

The $2 is irrelevant! Its a tip that is divided between the 3 men.

 Thats the answer..
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efirkey

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Re: Brain Twister need help
« Reply #24 on: October 13, 2006, 01:00:52 PM »
or,

they actually end up paying the gym one third of $25 = $8.33 each

they end up with $1 each so $9.33 is now accounted for out of the original $10.

the remaining 67 cents each goes to the kid

8.33
1.00
0.67
----
10.00 each

Yeah, they each end up paying $9.33 not $9