From: radams@BNR.CA (Rodney Adams)
Newsgroups: rec.org.mensa
Subject: Re: Ad in Air & Space
Date: 8 Oct 92 15:37:13 GMT
Reply-To: "Rodney Adams" <RADAMS@BNR.CA>
Organization: Bell-Northern Research, Ltd.

In article <BvrHon.D1q@ulowell.ulowell.edu>, akearns@cs.ulowell.edu (Adam Kearns) writes:
|> 
|> 	Hi.  I saw an ad in Air & Space magazine (and I'm sure it's in
|> others) from Mensa.  It said "Take This Instant Test To See If You're A Genius."
|> and had this problem
|> 
|> 	      0   1   2   3   4   5   6   7   8   9   =  1
|> 
|> You're supposed to put in + and - signs in the correct places
|> so the expression is true (the sum will equal 1.)  It also states that
|> "This problem stups 45% of the Mensa members who try it.  And they all
|> have IQs in the top 2% nationwide."  I looked at it, and solved it in 
|> less than five minutes.  I was just wondering if 1) they're 
|> exaggerating the 45% figure, 2) there is supposed to be a time limit
|> on the problem, or 3) this means I'm a genius.  I'm not a member, but
|> I was just curious to know what you people thought.  I'll put my answer below
|> in case I made a mistake, someone can correct me (although I'm pretty sure
|> it's right else I wouldn't post it all over the world).  BTW, I din't think
|> you were supposed to start a sentence with 'AND' .  
|> 
|> 						Adam Kearns
|> 						akearns@cs.ulowell.edu
|> 						akearns@ll.mit.edu
|> 
|> -------------------------------------------------------------------------------
|> I got       0 + 1 + 2 + 3 + 4 + 5 - 6 - 7 + 8 - 9 = 1
|> 0 + 1 = 1 + 2 = 3 + 3 = 6 + 4 = 10 + 5 = 15 - 6 = 9 - 7 = 2 + 8 = 10 - 9 = 1
|> P.S.  I would also be interested in other valid answers.

I came up with 0 - 1 - 2 + 3 + 4 - 5 - 6 + 7 - 8 + 9 = 1 in about a minute 
or so.  I would imagine there are several, if not many, more.  

So, to answer your questions:
1) This is an advertisement.  Two out of three doctors can be cited as 
   recommending one medicine over another, while two out of three other
   doctors can be cited as recommending the competing medicine.  In this
   case, a certain problem was chosen which 9 out of a certain population
   of twenty 20 Mensans could not answer.
2) There is no time limit stated, and no reason to infer one.
3) Even if the question was representative, being in the top 55% of the 
   top 2% is not enough to classify you as a genius.  You may be, but
   not by answering this one problem. 
----------------------------------------------------------------------

I tried posting the above yesterday, but after half an hour of waiting
I finally gave up on it, locked up my computer, and went home.  This 
morning, a window had popped up showing a fatal NNTP error, so I am
posting this pretty much as a test right now because either nobody has
responded to Adam's question by now, or something is still wrong with
my link to USENET.

Anyway, my first instinct for the problem above was to suspect some trick.
In that vein, I sought a different solution and found the following in
another minute or two:

 0 + 1 - 2   3 - 4 + 5 - 6   7 + 8   9 = 1

The following set of "normal" answers I obtained using a simple program:

0 -1 -2 -3 -4 -5 +6 -7 +8 +9 = 1
0 -1 -2 -3 +4 +5 +6 -7 +8 -9 = 1
0 -1 -2 +3 -4 +5 -6 +7 +8 -9 = 1
0 -1 -2 +3 -4 +5 +6 -7 -8 +9 = 1
0 -1 -2 +3 +4 -5 -6 +7 -8 +9 = 1
0 -1 +2 -3 -4 -5 +6 +7 +8 -9 = 1
0 -1 +2 -3 -4 +5 -6 +7 -8 +9 = 1
0 -1 +2 -3 +4 -5 -6 -7 +8 +9 = 1
0 -1 +2 +3 -4 +5 +6 +7 -8 -9 = 1
0 -1 +2 +3 +4 -5 +6 -7 +8 -9 = 1
0 -1 +2 +3 +4 +5 -6 -7 -8 +9 = 1
0 +1 -2 -3 -4 -5 +6 +7 -8 +9 = 1
0 +1 -2 -3 -4 +5 -6 -7 +8 +9 = 1
0 +1 -2 -3 +4 +5 +6 +7 -8 -9 = 1
0 +1 -2 +3 -4 +5 +6 -7 +8 -9 = 1
0 +1 -2 +3 +4 -5 -6 +7 +8 -9 = 1
0 +1 -2 +3 +4 -5 +6 -7 -8 +9 = 1
0 +1 +2 -3 -4 +5 -6 +7 +8 -9 = 1
0 +1 +2 -3 -4 +5 +6 -7 -8 +9 = 1
0 +1 +2 -3 +4 -5 -6 +7 -8 +9 = 1
0 +1 +2 +3 -4 -5 -6 -7 +8 +9 = 1
0 +1 +2 +3 +4 -5 +6 +7 -8 -9 = 1
0 +1 +2 +3 +4 +5 -6 -7 +8 -9 = 1


----------------------------------------------------------------------

Rodney G. Adams
The opinions expressed above are not necessarily those of my employer.
As if you didn't already know that....