View of /trunk/NationalProblemLibrary/UVA-Stat/setStat212-Homework06/stat212-HW06-12.pg

    1 ## DESCRIPTION
    2 ##  Statistics: Probability
    3 ## ENDDESCRIPTION
    4 
    5 ## KEYWORDS('statistics', 'probability')
    6 ## naw tagged this problem.
    7 
    8 ## DBchapter('Continuous Probability Distributions')
    9 ## DBsection()
   10 ## Date('6/28/2005')
   11 ## Author('Nolan A. Wages')
   12 ## Institution('UVA')
   13 ## TitleText1('Statistics for Management and Economics')
   14 ## EditionText1('6')
   15 ## AuthorText1('Keller, Warrack')
   16 ## Section1()
   17 ## Problem1()
   18 
   19 
   20 DOCUMENT();        # This should be the first executable line in the problem.
   21 
   22 loadMacros(
   23 "PG.pl",
   24 "PGbasicmacros.pl",
   25 "PGchoicemacros.pl",
   26 "PGanswermacros.pl",
   27 "PGnumericalmacros.pl",
   28 "PGstatisticsmacros.pl",
   29 "PGauxiliaryFunctions.pl"
   30 );
   31 
   32 TEXT(beginproblem());
   33 $showPartialCorrectAnswers = 1;
   34 ## install_problem_grader(~~&std_problem_grader);
   35 
   36 $ans1 = 0;
   37 while ($ans1 < 0.002) {
   38 $a = random(3500,6500,100);
   39 $b = $a+random(100,300,50);
   40 $c = random(100,300,50);
   41 $ans1 = normal_prob($a, 'infty', mean=>$b, deviation=>$c);
   42 }
   43 
   44 BEGIN_TEXT
   45 $PAR
   46 The lifetime of lightbulbs that are advertised to last for $a hours are
   47 normally distributed with a mean of $b hours and a standard deviation
   48 of $c hours.  What is the probability that a bulb lasts longer than
   49 the advertised figure?
   50 $PAR
   51 Probability =  \{ans_rule(15)\}
   52 $PAR
   53 
   54 END_TEXT
   55 
   56 ANS(num_cmp($ans1));
   57 
   58 
   59 
   60 ENDDOCUMENT();       # This should be the last executable line in the problem.