Im not in an MBA program yet, but i too have a low UG gpa and have asked the same question of students. Some schools have grade non disclosure, so you cant tell a potential employer your MBA grades until after you graduate ( most top schools have this) in this case UGPA is very important.
McKinsey will ask for your GPA on its application. Not all of them do but they may ask you in an interview, that is if you can get one. I'm not sure about IB but i imagine its the same....certain companies care enough to ask you pre interview, other may never ask.
So what the hell are we supposed to do?
well networking will be even more important for us. I'm not sure how low your gpa is but if a company gets to know you and likes you enough they may over look it if you have the right skills and are otherwise an excellent fit for them.
Another thing is that you have to rock your classes. While you aren't supposed to disclose your grades there are all kinds of titles and awards that while not giving away your exact grades do show that you are in the top 20% or even 10% of your class. Im making the following example up but if you put Presidential Scholar on your resume and you go to Duke, people know you have above a 3.75 or whatever.
Grade inflation during graduate school unfortunately makes your grad GPA less meaningful, but if its from a name brand school its will help regardless. Also a sky high GMAT can make it easier on you. Ideally you should have 700+ for most MC and IB jobs.
Hope this helps and its a great question. i hope we get some other insights
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