I wouldn't be totally panicked about this if the rest of your profile is stellar, and you do an awesome job communicating that through your application.
While the GMAT can be a way to separate yourself, it is also the admissions way to assess your ability to do the work. For the latter, 45 is on the margin but ok.
They are not going to think that you're going to flunk out of the math courses. Plus you have an industrial engineering with decent grades, so with that background so it appears you've done a little bit of math in your time.
Your percentile is low because there are a whole lot of people who are really great at math taking the exam.
I'm curious to learn about where you heard the 70% cut off number.
If you have the option to reapply next year, then you might want to just go for it. That is code for if you are under 30.
You would be in a different position going in with a 740. But with Trans Continental travel I can understand how that would be a major onus to really study for this again.
I would recommend that you really focus on doing an awesome job with the essays, your resume, and coach to your recommenders around anecdotes that separate you. You have to nail the app.
By the way, you had not mentioned it but I forgot to ask. If you are Asian or Indian then retake the exam absolutely, without question.
Farrell Dyan Hehn, MBA
Admissions Consultant & Verbal Strategist MBAPrepCoach.com