I believe it does uncompress RARv3 files... but how about trying it?
By the way, this compression format is useless and it does not hurt to tell it to people sending such files:
For more than five years, the best compression rates have been obtained with the XZ format (supported by FileRoller). If you do not care that much about the compression rate and want to squeeze many data in no time, just use the GZIP format.
