Answer: If you don’t know her qualifications, then you are missing critical information. Almost every job has a range of starting salaries, and applicants with more knowledge or experience will have greater leverage in negotiating. Your boss may have made an unwise comment, or perhaps you missed his exact meaning. To get accurate information, talk to your human resources manager without mentioning your well-paid colleague.
For example: “"When I was hired, I understood that everyone in this position started at the same pay level. That doesn’t seem to be the case, so could you explain how starting salaries are actually determined?"
Then, if you still feel underpaid, ask how you can qualify for a raise. Trying to improve your own pay will be more productive than continuing to fume about your co-worker’s compensation.
Concerned about your own compensation? Here are some tips that may help: How to Ask for a Raise.