Converting Javascript Text-Field Quiz to Radio Button Quiz

Hi,

I'm using a simple quiz script with text-fields, if the user's answer matches an array of answers they get scored appropriately.

I'd like to use this same system, but with radio buttons instead. Users click on a multiple-choice answer radio button, if it matches the corresponding item in an array of answers (answer "a"/"b"/"c" for example) they get scored appropriately. Here's my script using text-fields:

<SCRIPT language=JavaScript>
<!--
var numQues = 10;
var answers = new Array(10);
answers[0] = "a";
answers[1] = "b";
answers[2] = "a";
answers[3] = "a";
answers[4] = "b";
answers[5] = "b";
answers[6] = "a";
answers[7] = "a";
answers[8] = "b";
answers[9] = "b";

function getScore(form) {
  var score = 0;

  for (i=0; i<numQues; i++) {
    if (form.elements[i].value == answers[i]) {
      score++;
    }
  }

  score = Math.round(score/numQues*100);
  form.percentage.value = score + "%";
  var correctAnswers = "";
  for (i=1; i<=numQues; i++) {
    correctAnswers += i + ". " + answers[i-1] + "\r\n";
  }
  form.solutions.value = correctAnswers;
}

// -->
</SCRIPT>

The HTML form goes like this:
<FORM name=quiz>
<input type="text" name="q1" size="25">
<input type="text" name="q2" size="25">
<input type="text" name="q3" size="25">

... and so on up to question 10 ...

<INPUT size=5 name=percentage>
<TEXTAREA name=solutions rows=13 wrap=virtual cols=30></TEXTAREA>
<input onClick=getScore(this.form) type=button value="Grade Me" name="button">
<INPUT type=reset value=Clear>
</FORM>

Please provide the script to have this quiz work with multiple-choice radio buttons with answers a, b, c. Thankyou!

Best Regards,

Jeremy