Mathmatical Riddles

[ks]

So does anyone here know of some mathmatical riddles or some brain teasers in the math department? My cousin, who is a math teacher was looking for some fun ones to give her class and I thought who better to ask than you guys. Just wonderin'....any help much appreciated. Thanks;)







ks

[Bootsy Whoosh]

Here's one:

The Missing Dollar:
3 men walk into a hotel and ask for rooms. The desk clerk regretfully informs them that he only has one room left, but he says that he will allow the men to share the room. The room cost $30, so the men split the cost evenly 3 ways. Later in the evening, the desk cleark realizes that he has made a mistake, and that the cost of the room the men are staying in is only $25. He gives the bell boy 5 one dollar bills, and instructs him to refund the men the $5. The bell boy thinks dividing the money between the 3 men will be a hassle, so he just gives each man back $1, and keeps the remaining $2 for himself. Now each man has spent $9, which makes a total of $27, and the bellboy has $2, which makes a total of $29. So where's the missing dollar?

I'll post the answer a little later since people here might want to try to solve it. ks if you need the answer sooner I can PM it to you. I can probably find some more math riddles later. If I do I'll post 'em here.

[F*O*L 1988]

Oh my gosh, I could never in a million years figure that out! Math is my all time worst subject. :rolleyes:

[AllIWantIsYourClutch]

Originally posted by Bootsy Whoosh
Here's one:

The Missing Dollar:
3 men walk into a hotel and ask for rooms. The desk clerk regretfully informs them that he only has one room left, but he says that he will allow the men to share the room. The room cost $30, so the men split the cost evenly 3 ways. Later in the evening, the desk cleark realizes that he has made a mistake, and that the cost of the room the men are staying in is only $25. He gives the bell boy 5 one dollar bills, and instructs him to refund the men the $5. The bell boy thinks dividing the money between the 3 men will be a hassle, so he just gives each man back $1, and keeps the remaining $2 for himself. Now each man has spent $9, which makes a total of $27, and the bellboy has $2, which makes a total of $29. So where's the missing dollar?

I'll post the answer a little later since people here might want to try to solve it. ks if you need the answer sooner I can PM it to you. I can probably find some more math riddles later. If I do I'll post 'em here.

ARGH!! I knew the answer to that and I forgot it!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

[Kay Scarpetta]

Originally posted by NancyRulz24
ARGH!! I knew the answer to that and I forgot it!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

So did I!!!!! :p

[Czas na Zywiec]

Originally posted by Bootsy Whoosh
Here's one:

The Missing Dollar:
3 men walk into a hotel and ask for rooms. The desk clerk regretfully informs them that he only has one room left, but he says that he will allow the men to share the room. The room cost $30, so the men split the cost evenly 3 ways. Later in the evening, the desk cleark realizes that he has made a mistake, and that the cost of the room the men are staying in is only $25. He gives the bell boy 5 one dollar bills, and instructs him to refund the men the $5. The bell boy thinks dividing the money between the 3 men will be a hassle, so he just gives each man back $1, and keeps the remaining $2 for himself. Now each man has spent $9, which makes a total of $27, and the bellboy has $2, which makes a total of $29. So where's the missing dollar?

I'll post the answer a little later since people here might want to try to solve it. ks if you need the answer sooner I can PM it to you. I can probably find some more math riddles later. If I do I'll post 'em here.

I know that one! I just read it, but I'll keep my mouth shut. :D<~~Opposite of this. :lol:

[Ags2000]

Let me take a stab at this.

Even though they were each given a dollar back, they still had given a total of $30.

At first they all gave $10 for a total of $30. Then they were each given $1 back. So the total that they paid (including the $2 to the bellboy) was $27 or $9 each. The remaining $3 is the money that they got back.

The "extra dollar" never went anywhere, you just had to look at it differently.


D

[Bootsy Whoosh]

Originally posted by Ags2000
Let me take a stab at this.

Even though they were each given a dollar back, they still had given a total of $30.

At first they all gave $10 for a total of $30. Then they were each given $1 back. So the total that they paid (including the $2 to the bellboy) was $27 or $9 each. The remaining $3 is the money that they got back.

The "extra dollar" never went anywhere, you just had to look at it differently.
D

Well your last statement is correct, but I'm not sure if the first part if right. It's not the answer I have, but that doesn't mean yours is wrong. However, thinking it out, I do think it's off the mark, but not by much. It could be right though, and I'm simply confusing myself :crazy: lol. At any rate it's not the "official" answer.

[Warm & Fuzzy]

Got it! But I cheated....lol. Don;t stroll down and read the rest I have to say! (If you dont; want to)































































The facts in this riddle are clear: There is an initial $30 charge. It should have been $25, so $5 must be returned and accounted for. $3 is given to the 3 friends, $2 is kept by the bellhop - there you have the $5. The trick to this riddle is that the addition and subtraction are done at the wrong times to misdirect your thinking - and quite successfully for most. Each of the 3 friends did indeed pay $9, not $10, and as far as the friends are concerned, they paid $27 for the night. But we know that the clerk will tell us that they were charged only $25 and when you add the $3 returned with the $2 kept by the bellhop, you come up with $30.

[JoJoJoJoJoJoJoJoJo]

Ok, well, i didn't do math...but here's my answer:

Alright, well the hotel man has 25$
the bell boy has 2$
and the men have 3$

So, the missing dollar isn't really missing

Here's the math, I thi nk?

30-5=25 (discount price)
Take the 5 that was subtracted and give three of it to the men
5-2= 3
Remaing of the 5: 2

25+3+2=30$

Umm..ok, i confused myself w/ the math...but just don't look @ it mathmatically and you'll find it!

[Ags2000]

Originally posted by JoJoJoJoJoJoJoJoJo
Ok, well, i didn't do math...but here's my answer:

Alright, well the hotel man has 25$
the bell boy has 2$
and the men have 3$

So, the missing dollar isn't really missing

Here's the math, I thi nk?

30-5=25 (discount price)
Take the 5 that was subtracted and give three of it to the men
5-2= 3
Remaing of the 5: 2

25+3+2=30$

Umm..ok, i confused myself w/ the math...but just don't look @ it mathmatically and you'll find it!


Sounds good to me. I think that's what I was trying to say :)


D