ElectricPavlov

Well yah......22.5           it's just not a 'factor'          ooops....fixed..

.Miscopied from my scratch pad....  

.......AND...... you lost the bet.  

Your question states the counterfit one weighs 'different'  .....if you do not know in what manner the counterfit one weighs 'different'  (i.e. it could weigh MORE than gold ....maybe depleted uranium or something) , then the minummwould be as follows:

  .

      split the bars up two per side.......One side will be DIFFERENT......

       One side split up will be either:      =.......we know those are both genuine     (second weighing)

                                                             0r not =   (means the other two were genuine)

      third weighing with a genuine one and one from the second pair   if =   both genuine and the other from the second pair is counterfit

                                                                                                                       if not = then this one is cfit

Sooooo.... it will take THREE weighings if you do not know how the counterfit bar differs from the others (heavier or lighter)

x+y = -15   y = -15-x

xy=-34

x((-15-x) = -34

-x^2 -15x + 34 = 0

x^2 +15x -34 = 0

(x-2)(x+17) = 0          x = 2 and -17

Total circumf = 2 pi r

                     = 40 pi

Fraction of circumference  =   45/40pi        

2pi radians in a full circle.....the fraction of this  is       45/40pi * 2pi = 90/40 R = 2.25R

36 w x 48 hr = 1728 worker hours to complete the job

1728 w h /24 w = 72 hrs for only 24 workers 

Just in case you are unsure :

density =  mass/volume     

9 x 10 = 90    divisible by  15

99 x 100 = 9900    divisible by 4 and 15

999 x 1000 = 999 000  divisible by 4 and 15      see a pattern here?

B:  2400 cents /80 cents/magnet  = 30 magnets     2400/120 = 20 magnets      

          4800 total / (30 + 20 magnets) = 96 cents/magnet

Math 'Poll'  

Area of an Octagon =  A = 2(1+sqr2)a2     where a = side length    3.5 /8 = .4375 side length

A=.9242 units^2