View Full Version : A puzzle

08-14-2003, 04:36 PM
What other $? 27 minus 2 equals 25 plus 5 overcharged is 30...

But good one anyway.

tony barnhill
08-14-2003, 04:49 PM
I've had high school seniors working on that one all day - gave them the entire 96 minute class to figure it out....from 4.0 students to Special Education students in each class - none has figured out what you 2 guys did!

Mickey Richaud
08-14-2003, 05:18 PM
UH....Is that good or bad?

08-14-2003, 05:30 PM
The problem statement is flawed. The $2 the bellboy has is already included in the $27 the men have now paid for their rooms. Thus, they paid $27, of which $25 was for the room and $2 is in the bellboy's pocket. Add the $3 the got back to the $27 they paid and you get $30. images/icons/grin.gif

tony barnhill
08-15-2003, 03:22 AM
3 salesmen go out of town for business trip...they decide to share a hotel room...clerk tells them it is $30 for the night so they each give her $10....after they get to their room, clerk realizes she overcharged them so she calls bellboy over, gives him $5 to take to salesmen's room....he can't figure out how to split so he pockets $2 & gives each of the salesmen $1
...that means each salesman paid $9 for his room
bellboy kept $2
total: $29
where's the other dollar?

Mickey Richaud
08-15-2003, 03:35 AM
Honest, Tony - I didn't take it!

Actually, I think the three salesmen have it. They may have "paid" $9 each for the room, but it only cost them $8.33 1/3 each (I think)

08-15-2003, 09:36 AM
You must be kidding Tony!?!

tony barnhill
08-18-2003, 09:33 AM
Nope, I'm not kidding! I'm focusing this 9 weeks on developing 'cognitive thinking' skills among my students &, while worded a specific way, the question was't flawed - just written like that to cause them to think differently - which they couldn't do....they can do all the math problems in all their math books & all that their math teachers give them...they just can't think outside the box!

08-18-2003, 12:26 PM
<blockquote><font size="1" face="Verdana, Arial">quote:</font><hr>Originally posted by tony barnhill:
they just can't think outside the box!<hr></blockquote>

Which is the basic problem with most of the HS and basic college students these days.

I've hired and fired "educated" people who could ace tests but hadn't a clue how to apply the knowledge they supposedly had. If nobody's said it, thank you Tony for actually trying to teach them to apply some knowledge.

08-18-2003, 01:06 PM
<blockquote><font size="1" face="Verdana, Arial">quote:</font><hr>Originally posted by aerog:

Which is the basic problem with most of the HS and basic college students these days.


Is it really just theses days? Haven’t educational “systems” always stressed information regurgitation over thinking?


08-18-2003, 01:47 PM
One of the best things I did years ago wwhen in college was work in the student computer center as a coding helper. I got to look at and try to figure out any problems that students and faculty had. Taught me not to think in terms of just what I'd learned. Came to the conclusion, after seeing so many struggling students, that a monkey could learn to code but not many people are skilled at solving problems.

08-18-2003, 05:30 PM

I can't really figure the problem out. If the three men were charged $30 for a $25 dollar room and they were refunded the 5 dollars and the bellboy gave himself a $2 tip then the math works out perfectly every time.Why would the students have a problem with it its not critical thinking its just common sense.

Cheers, graemlins/thirsty.gif graemlins/driving.gif

08-18-2003, 08:27 PM
<blockquote><font size="1" face="Verdana, Arial">quote:</font><hr>Originally posted by waltesefalcon:
Why would the students have a problem with it its not critical thinking its just common sense.


The problem is in the phrasing of the question “where's the other dollar?” As you pointed out the math works out perfectly, there is no “other dollar”.

By asking about the “other dollar” the students, who have been conditioned to expect straightforward math problems, believed it exists. Since they expect there to be an “other dollar” they continue their futile search for it.

I’m sure many of the students would do the math just fine if it were presented differently. I’d suspect that some of them would even catch the problem if it were presented to them in a different venue, free of the expectations of the classroom.

I believe that society would be better served if more teachers follow Tony’s example and presented lessons in critical thinking.


08-18-2003, 10:47 PM
Bizarre but I guess I was just raised a little differently. I suppose you could say my dad didn't raise no fool. Anyway yeah I see the phrasing problem, and how tony set up the problem to be intentionally confusing to someone who wasn't paying close enough attention to it, or as you said PC someone conditioned to expect a certain format.

Cheers, graemlins/thirsty.gif graemlins/driving.gif

08-18-2003, 11:30 PM
It's like the "missing fence post" problem.
A fence with a post every 5 feet on a 200 x 300 lot. How many posts to make a fence all around?
Math really is a different language from verbal stuff.

08-18-2003, 11:38 PM
About the teaching of things....
I was talking to a fellow from Paraguay. He said that normal curriculum for middle schoolers included a course in Logics. and he wasn't talking semiconductors.
We in the USA need that as well as a mandatory course in Personal Economics. (checkbooks, bank accts, compounded interest, etc.)
Hmmm I seem to have moved out of the Humor category. sorry.

tony barnhill
08-19-2003, 12:06 AM
That's okay, David....2nd 9 weeks, my students get to play my "welcome to Life" game...resume, job hunting in paper, interview, hire, checking account, savings account, apartments, utilities, etc, etc, etc,...I'm their father/mother/banker/landlord/utility company/car dealer/insurance agent, etc, etc, etc....&, over the 9 weeks, thery get to spin the bottle for a good thing (i.e., promotion) or a bad thing (speeding ticket)....kids love it & learn about life from it....I've had graduates come back & talk about how it prepared them for moving out of mom's house....