strFldr="s:\"
dtMod=DateAdd("d",-90,Date)
WScript.Echo "Finding files modified since " & dtMod
Set objFSO=CreateObject("Scripting.FileSystemObject")
Set objFldr=objFSO.GetFolder(strFldr)
Set colFiles=objFldr.Files
iCount=0
iSubTotal=0
iSubSize=0

For Each f In colFiles
    iCount=iCount+1
    If f.DateLastModified >= dtMod Then
        iSubTotal=isubTotal+1
        iSubSize=iSubSize+f.size
    End If
Next

WScript.Echo "Found " & iSubTotal & " files modified since " &_
 dtMod & " out of " & iCount &_
 ". Approximate average size of each file " &_
  iSubSize\isubTotal & " bytes."