Cybervanes Cybervanes - 4 months ago 12
PHP Question

Grading using weighted averages in php

How could I grade this test with php? I need a percentage score...

I have an array of questions containing the correct / incorrect bool and the corresponding weight.

Do I need to find the average of correct answers first?

What would the equation be?

$questions = array(
0=>array(
'Question'=>"Some Question",
'Correct'=>true,
'Weight'=>5,
),
1=>array(
'Question'=>"Some Question",
'Correct'=>false,
'Weight'=>5,
),
2=>array(
'Question'=>"Some Question",
'Correct'=>true,
'Weight'=>4,
),
3=>array(
'Question'=>"Some Question",
'Correct'=>true,
'Weight'=>0,
),
4=>array(
'Question'=>"Some Question",
'Correct'=>false,
'Weight'=>5,
),
5=>array(
'Question'=>"Some Question",
'Correct'=>true,
'Weight'=>4,
),
);
$weights = array(
0=>0
1=>0
2=>.05
3=>.20
4=>.25
5=>.50
);
$totalQuestions=0;
$correctAnswers=0;
$points=0;
foreach($questions as $question){
$totalQuestions++;
if($question['Correct']){
$correctAnswers++;
$points = $points = $weights[$question['Weight'];
}
}

Answer

You can calculate the amount of weights the candidate earned (i.e. the points you have) and then the total weights possible (i.e. a perfect score).

Then you can divide the candidate score by the total score:

Score = Candidate score / Total Score

From there you can calculate the percentage:

Percentage = Score * 100

Using your code:

$totalQuestions=0;
$totalWeights=0;
$correctAnswers=0;
$weightsEarned=0;
foreach($questions as $question){
    $totalQuestions++;
    $totalWeights+=$weights[$question['Weight']];
    if($question['Correct']){
        $correctAnswers++;
        $weightsEarned += $weights[$question['Weight']];
    }
}

echo "Score Overview: ";
echo "<br/>Weights Earned: " . $weightsEarned;
echo "<br/>Correct Answers: " . $correctAnswers;
echo "<br/>Total Weights Possible : " . $totalWeights;
echo "<br/>Percentage Earned: " . ($weightsEarned / $totalWeights) * 100;
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