function quiz() {
    var i = 0
	var total = document.forms.length-1;
	var ncorrect = 0;
	var response = new Array( total );
	var theForms = new Array( total );
	var answer = new Array( total );
	var resultados = new Array( total );
		  
	for ( i=1; i <= total;i++ ) {
	theForms[i]=document.forms[i-1];
	}
	
	for ( i=1; i <= total; i++ ) {
   	response[i]=theForms[i].answer.selectedIndex;
	}
	
	for ( i=1; i<=total;i++ ) {
	answer[i]=theForms[i].correct.value;
	}
	
	var flag=true;
	  for ( i=1; i <= total; i++ ) {
		 	if ( response[i] == 0 ) {
		  		alert ( "Debe contestar a todas las preguntas. \nNo ha contestado a la pregunta:  "+i+"" );
		  		flag=false;
		  	}
	  }
	if ( flag ) { 
		for ( i=1; i <= total; i++ ) { 
			if ( response[i]==answer[i] ) {
				ncorrect++;
				document.total.score.value = ncorrect;
				var per =  Math.round( ( ncorrect / total ) * 8 );
				document.total.percent.value = per;
				document.total.outof.value = total;
			}
		}
		
	var correctos = document.total.score.value = ncorrect;
	if ( ( correctos == 7 ) || ( correctos == 8 ) ) {
			document.getElementById('7').style.display = 'block';
			document.getElementById('6').style.display = 'none';
			document.getElementById('4').style.display = 'none';
			
		}
		else if ( correctos == 4 || correctos == 5 || correctos == 6) {
			document.getElementById('7').style.display = 'none';
			document.getElementById('6').style.display = 'block';
			document.getElementById('4').style.display = 'none';
			}
		else if (correctos < 4 ) {
			document.getElementById('7').style.display = 'none';
			document.getElementById('6').style.display = 'none';
			document.getElementById('4').style.display = 'block';
			}
		var correctos = document.total.score.value = ncorrect;
		if (correctos < 8 ) {
			document.getElementById('OcultarResults').style.display = 'block';
			}
} 
	} //end if ( flag )
				 
// -->