can I run tar on a .gz file? e-engineer does it in directions

I'm trying to follow the directions by e-ngineer on installing mysql at: http://www.e-gineer.com/instructions/install-mysql3xx-on-linux.phtml After downloading the mysql(version).tar.gz file, I'm told to un tar it with tar xzf mysql(version).tar.gz . Is that a missprint or am I wrong? When I run this command I get an error saying: gzip: stdin: not in gzip format tar: Child returned status 1 tar: Error exit delayed from previous errors I tried running: "gunzip -c mysql(version).tar.gz" but also got errors saying its not in that format. I tried downloading different mysql files from other sources, but get same messages. Also, the file is suppose to be 7.8 MB, but after downloading it it only shows to have 46070K , that is weird too, and they all are the same size.