### Re: access to student responses between evaluations

by Hedley Pinsent -I think it is ok now. I am quite pleased with how it works.

I tried lots of stuff; this is probably the only way to do it.

The subroutines seem to make a copy everything they receive, and are very reluctant to give anything back.

Thanks - hp

## DESCRIPTION

## Statistics

## ENDDESCRIPTION

## KEYWORDS('Statistics','Confidence Intervals')

## Tagged by

## DBsubject('Statistics')

## DBchapter('Confidence Intervals')

## DBsection('Sample Size - Proportion')

## Date('')

## Author('')

## Institution('')

## TitleText1('')

## EditionText1('')

## AuthorText1('')

## Section1('')

## Problem1('')

DOCUMENT();

loadMacros(

"PGbasicmacros.pl",

"PGnumericalmacros.pl",

"PGstatisticsmacros.pl" ,

"PGauxiliaryFunctions.pl",

"MathObjects.pl",

"parserMultiAnswer.pl"

);

TEXT(beginproblem());

$showPartialCorrectAnswers = 1;

$ppercent = random(40,80,10);

$p = $ppercent / 100;

$confidence = list_random(80,90,95,98,99);

$deg = $confidence / 100;

$E = list_random (1,2,3,4,5,6,8,10);

$dE = $E /100;

$z=udistr (0.5 - $deg/2);

#$ans1 = $z;

$ans2 = ceil($p*(1 - $p)*($z/$dE )**2);

Context()->flags->set(

tolType => 'absolute',

tolerance => 0.0001

);

$ans1 = $z;

$ans12 = MultiAnswer( $ans1, $ans2 )->with(

singleResult => 0,

checker => sub {

my ( $correct, $student, $self ) = @_;

my ( $stu1, $stu2 ) = @{$student};

my $stuCalc = Compute("int(0.99999 + $p*(1 - $p)*($stu1/$dE)^2)");

my ( $cor1, $cor2 ) = @{$correct};

if ( abs($cor1 - $stu1)<0.01 && ( ($stuCalc == $stu2) || ($cor2 == $stu2) )) {

return [1,1];

} elsif ( abs($cor1 - $stu1)<0.01 ) {

return [1,0];

} elsif ( ($stuCalc == $stu2) || ($cor2 == $stu2) ) {

return [0,1];

} else {

return [0,0];

}

}

);

BEGIN_TEXT

It is claimed that $ppercent $PERCENT of households now subscribe to cable TV. You would like to verify this statement for your class in mass communications. You want an estimate within $E percentage points, with a $confidence $PERCENT level of confidence.

$BR

What z-value would you use?

\{ $ans12->ans_rule(25) \} $BR

How large of a sample is required? $BR

\{ $ans12->ans_rule(25) \} $BR \( \bar p (1 - \bar p) (\frac{z}{E})^2 \) $BR Additionally we always round up. $BR

END_TEXT

ANS( $ans12->cmp() );

ENDDOCUMENT();