este el HTML
<html>
<head>
<script type="text/javascript" src="jss.js"></script>
</head>
<body>
<form name="EvAlu">
<input type="texto" id="nota" value="4">
<input type="texto" id="asis" value="0">
<table width="96%" border="1" align="center" id="table">
<tr class="titulo_tabla">
<td width="2%">Nº</td>
<td width="15%">RUT</td>
<td width="*%">Nombre</td>
<td width="10%">Nota</td>
<td width="10%">Situación</td>
</tr>
<tr>
<td align="right">1</td>
<td align="right" >12811148-4</td>
<td> CRISTI MUÑOZ HELENE</td>
<td><input type="text" size="3" maxlength="3" name="N12811148" id="nombreText" value="0" onBlur="rango(this)" ></td>
<td>
<select name="nota12811148" id="no" onclick="valorAlText(this);">
<option selected value="1">Cursando</option>
<option value="2">Aprobado</option>
<option value="3">Reprobado</option>
<option value="7">Desertor</option>
<option value="8">Desertor Justificado</option>
</select>
</td>
</tr>
<tr>
<td align="right">2</td>
<td align="right" >13087423-1</td>
<td>PINO SALAZAR ANA LISSETTE</td>
<td><input type="text" size="3" maxlength="3" name="N13087423" id="nombreText" value="0" onBlur="rango(this)" ></td>
<td>
<select name="nota13087423" id="no" onclick="valorAlText(this);">
<option selected value="1">Cursando</option>
<option value="2">Aprobado</option>
<option value="3">Reprobado</option>
<option value="7">Desertor</option>
<option value="8">Desertor Justificado</option>
</select>
</td>
</tr>
<tr>
<td align="right">3</td>
<td align="right" >3038395-8
</td>
<td>ABARCA ESCOBAR JUAN</td>
<td><input type="text" size="3" maxlength="3" name="N3038395" id="nombreText" value="0" onBlur="rango(this)" ></td>
<td>
<select name="nota3038395" id="no" onclick="valorAlText(this);">
<option selected value="1">Cursando</option>
<option value="2">Aprobado</option>
<option value="3">Reprobado</option>
<option value="7">Desertor</option>
<option value="8">Desertor Justificado</option>
</select>
</td>
</tr>
<tr>
<td align="right">4</td>
<td align="right" >14132397-0</td>
<td>ABELLEIRA PERALTA MILLARAI</td>
<td><input type="text" size="3" maxlength="3" name="N14132397" id="nombreText" value="0" onBlur="rango(this)" ></td>
<td>
<select name="nota14132397" id="no" onclick="valorAlText(this);" >
<option selected value="1">Cursando</option>
<option value="2">Aprobado</option>
<option value="3">Reprobado</option>
<option value="7">Desertor</option>
<option value="8">Desertor Justificado</option>
</select>
</td>
</tr>
</table>
</form>
</body>
</html>
este es el js modificado
function rango(id){
valor=parseInt(id.value,10);
notaini=window.document.EvAlu.nota.value;
cantFilas = document.getElementById("table").rows.length;
for(i=0;i<cantFilas;i++){
if (notaini<=valor){
id.style.background="#0FF";
id.style.color="#00F";
var o = document.createElement('input');
o.type = "text";
o.name = "lalala";
o.value = "Aprobados";
document.getElementById('no').appendChild(o);
document.getElementById('no').style.visibility = 'hidden';
return;
}else{
id.style.background="#F00";
id.style.color="#00F";
document.getElementById('no').selectedIndex[i] =2;
return;
}
}
id.style.background="#FFF";
id.style.color="#000";
return true;
}
function valorAlText(combo)
{
var text = document.getElementById('nombreText');
text.value = combo.options[combo.selectedIndex].value;
}