View of /trunk/NationalProblemLibrary/Rochester/setVectors0Introduction/ur_vc_0_7.pg

    1 ## DESCRIPTION
    2 ##   Flux of a Population
    3 ## ENDDESCRIPTION
    4 
    5 ## KEYWORDS('Flux', 'Increase', 'Decrease')
    6 ## Tagged by nhamblet
    7 
    8 ## DBsubject('Elementary Mathematics')
    9 ## DBchapter('Numbers')
   10 ## DBsection('Integers')
   11 ## Date('5/30/2000')
   12 ## Author('Joseph Neisendorfer')
   13 ## Institution('Rochester')
   14 ## TitleText1('')
   15 ## EditionText1('')
   16 ## AuthorText1('')
   17 ## Section1('')
   18 ## Problem1('')
   19 
   20 DOCUMENT();        # This should be the first executable line in the problem.
   21 
   22 loadMacros("PG.pl",
   23            "PGbasicmacros.pl",
   24            "PGchoicemacros.pl",
   25            "PGanswermacros.pl",
   26            "PGauxiliaryFunctions.pl");
   27 
   28 TEXT( beginproblem() );
   29 $showPartialCorrectAnswers = 1;
   30 
   31 #Array of choices
   32 @choices = ( "Persecuted",
   33              "Attracted by the promise of a better life",
   34        "Anti-social",
   35        "Born"
   36      );
   37 
   38 #Array of 0 .. 3 in random order
   39 @permutation = NchooseK(4,4);
   40 
   41 #Permute the choices
   42 @randomChoices = @choices[@permutation];
   43 
   44 #The following few lines ensure that the letter representing
   45 #the correct answer is also properly randomized
   46 @randomAnswers = @ALPHABET[&invert(@permutation)];
   47 $ans = $randomAnswers[3];
   48 
   49 BEGIN_TEXT
   50 The population of Elves in Lorien is constant. If five Elves per day cross outward over the boundary of
   51 Lorien, and none ever return, then we can conclude that Elves in Lorien are being:
   52 $PAR
   53  \{ans_rule(10)\}
   54 END_TEXT
   55 
   56 TEXT(&OL(@randomChoices));
   57 
   58 ANS(str_cmp($ans));
   59 
   60 ENDDOCUMENT();        # This should be the last executable line in the problem.