Can 165 songs take 15GB of space in a 30GB Ipod

You may have imported them in full size uncompressed Aiff (CD format). If that's the case you need to either rip your CDs over again into iTunes in a compressed format such as AAC or convert what you have and then update your iPod. Of the various options iTunes gives, AAC and MP3 are compressed formats so you lose some quality but gain space. AIFF (CD) and WAV are uncompressed so you gain quality at the expense of space. Apple Lossless falls somewhere in between, doesn't compress as much as AAC and MP3 so you gain some space but not as much, however it is claimed to give a quality which is the equal to CD. To find out what format your songs are in, right click on one in iTunes and choose Get Info and then the Summary Tab look at "Kind" and you will be able to see what format they are:
How To Choose Import Settings
How to convert a song to a different format

See also this post:

http://discussions.apple.com/thread.jspa?threadID=548570&tstart=0

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