Suppose in an interview somebody asks you about your undergraduate Grade Point Average (GPA). If it is very low what should you say? Also suppose your graduate school GPA is very high. Could I somehow use this to answer the low undergrad GPA?
You can always try:
I don't feel that my undergrad GPA accurately reflected my abilities, and here's how I fixed that in my graduate studies...
Everyone makes mistakes, the important thing is to acknowledge that it happened and explain how you fixed it going forward. You will eventually make mistakes at work, but gracefully recovering from those errors is a much more valuable skill than never making the mistake in the first place because it impresses clients and/or management.
In terms of businesses and customer service, this is called the Service Recovery Paradox.
The other nice thing about a bad undergraduate GPA is that it eventually doesn't matter on your resume, and chances are it won't come up in interviews after you are out of school for a few years.
Usually, the grad school GPA counts for a lot more than the undergrad GPA, assuming that you can make the case that your grad education is relevant to the field you work in. I had a pretty good grad GPA in engineering, and I can't remember a single prospective employer who did Oooh's and Aaah's over it.
Don't volunteer anything about your undergrad GPA, unless you like coming across as defensive, apologetic and possibly pathetic. The more explanations you give, the more you look like you're making excuses. If someone asks about your undergrad GPA, mention it with a pained grimace and immediately refocus the subject by saying that your grad GPA is a lot better.
You tell them your GPA. That's it. Never start defending yourself unprompted, because you're actually attacking yourself.
"My GPA was 2.5 [and my further silence indicates that this is a total non-issue that has no relation to my ability.]"
"My GPA was 2.5, and now I will nervously talk about how bad of a student I was and make revealing excuses."
Now of course if they prompt you to explain, you can answer in about two sentences, using your grad GPA to definitively prove that you improved and grew. If you spend more than two sentences, it really only raises the question of why that wasn't a sufficient explanation.
I think regardless of the actual GPA score, the important thing is to provide some explanation so the interviewer can put it in the right context.
For example, a bad GPA score may reflect that you are not good at exams if you can back it up with good practical knowledge and work experience.
Alternatively, a good GPA score may reveal some lack of practical knowledge but at least shows dedication to learning and commitment to achieving to your potential.
So the important thing is to bring out the positive aspects no matter what the score is, and address the concerns that the interviewer might have with any perceived shortcomings as reflected by the score.
But if the interviewer brings it up, you have to tell him, and your silence after that should underline that the GPA doesn't matter.
But still, there are few companies obsessed with GPA. In this case you must have good student projects, or any other experience in your resume to vouch for you. I mention my great graduation project, for example.
You can always say that there was so much to do and so many things that interested you at the time that you didn't always have time for academic stuff! It shows your interests. Bonus points if you can name something that can actually help you with this job or something you have in common with the interviewer. Or makes you an interesting person.