Using xsl:variable and text output type

Problem:   Compute the average grade of each student and the total average of the course

XML Input file (students.xml):

XSL Style Sheet :

<xsl:stylesheet version="1.0" 
                xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
  <xsl:output method="text"/>

  <xsl:template match="course">
    <xsl:apply-templates select="student"/>
    total average="<xsl:value-of select="(sum(//hw1) + 
                                          sum(//hw2) +
                                          sum(//final) +
                                          sum(//project))
                                          div (4*count(//student))"/>" 
  </xsl:template>

  <xsl:template match="student">
    <xsl:variable name="ave">
      <xsl:value-of select="(hw1 + hw2 + project + final) div 4"/>
    </xsl:variable>
    Student name="<xsl:value-of select="name"/>" 
    average="<xsl:value-of select="$ave"/>"
  </xsl:template>
</xsl:stylesheet>

Output file (grades.txt):

Student name="John Smith" 
        average="66.25"
Student name="George Lucas" 
        average="77.5"
Student name="Elizabeth Roberts" 
        average="73.75"
total average="72.5"