[ww-bugs] Bug 3586: New: Answer calculated incorrectly.

[bugzilla-daemon at webwork.maa.org]

http://bugs.webwork.maa.org/show_bug.cgi?id=3586

           Summary: Answer calculated incorrectly.
           Product: Problem Libraries
           Version: unspecified
          Platform: PC
               URL: /opt/webwork/courses/452_Spring_2016/templates/Library
                    /Mizzou/Finite_Math/Future_Value/ComputePMT5.pg_with_p
                    roblemSeed=865
        OS/Version: Windows
            Status: NEW
          Severity: normal
          Priority: P5
         Component: Library (OPL)
        AssignedTo: jj at asu.edu
        ReportedBy: travis at mc.edu
        Web browser ---
           version:


In the problem, 17 years is presumed for the length of the annuity but the
number of years appeared to have been a proposed variable...and which is
utilized in the answer computation.  My suggestion is to limit the number of
years a bit (so that you don't only have 2 years to save up it all).  You can
use the suggested code snippet below to replace what is there.  JT


...

$fv = Real(random(20000,31000,100));
$r = Real(random(3,7.5,0.01));
$dec = $r/100;
$i = $dec/12;
$t= Real(random(10,15,1));
$startyear = 18-$t;
$n = 12*$t;
$ans = $fv*(((1 + $r/1200)**(12*$t) -1)/($r/1200))**(-1);

Context("Currency");

$fv = Currency($fv);
$ans = Currency($ans);

##############################################################
#
#  Text
#
#

Context()->texStrings;
BEGIN_TEXT

Liz and Bob just had a baby named Isabelle, and they want to save enough money
for Isabelle to go to college.  Assume that they start making monthly payments
when Isabelle is 
\($startyear \) into an ordinary annuity earning \($r $PERCENT\), and they
calculate that they will need \($fv \) by the time Isabelle turns \(18\).  How
much should they deposit every month so that they reach their goal?

...

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