function clearExclusive(elem,anum) {
  for (i=0; i<elem.length; i++) {
    if (anum == elem[i].value) {
      elem[i].checked = false;
    }
  }
}

function clearNonExclusive(elem,anum) {
  for (i=0; i<elem.length; i++) {
    if (anum != elem[i].value) {
      elem[i].checked = false;
    }
  }
}

function checkTheBox(elem,anum) {
  for (i=0; i<elem.length; i++) {
    if (anum == elem[i].value) {
      elem[i].checked = true;
    }
  }
}

function checkThreeMax(elem,anum) {
  var numChk = 0;
  for (i=0; i<elem.length; i++) {
    if (elem[i].checked) {
      numChk++;
    }
    if (numChk > anum) {
      elem[i].checked = false;
      alert("Please select a maximum of three responses.");
    }
  }
}

function validateMaxResponses(elem,max_num) {
  var numChk = 0;
  for (i=0; i<elem.length; i++) {
    if (elem[i].checked) {
      numChk++;
    }
    if (numChk > max_num) {
      elem[i].checked = false;
    }
  }

  if (numChk > max_num) {
    alert("Please select a maximum of " + max_num + " answers.");
  }
}