Because this is a fragmented file ( .part1.rar ), you generally need all subsequent parts (e.g., .part2.rar , .part3.rar ) in the same folder to successfully extract the contents.
Are you trying to the remaining parts of this archive? business_development_magazine-6-1-4x.part1.rar
If you are looking for the source or more information on this specific file, could you clarify: Because this is a fragmented file (